THE MWROSCOQT‘C WTGfifiY 0F THE SKfiN
ANfi EXTERNAL EAR CF FEMS DOMESTiC‘JS

TM: for m Dogm cf M. S.
MCHSGAN- STATE UNEV’ERSETY
35mm H. Sh‘écklmd
1958

.A‘ :43 .

irativ

THE MICROSCOPIC ANATOMY OF THE SKIN AND

EXTERNAL EAR OF FELIS DOMESTICUS

by
James H. Strickland

A THESIS

Submitted to the College of Veterinary Medicine Michigan
State University of Agriculture and Applied Science
in partial fulfillment of the requirements
for the degree of

MASTER OF SCIENCE

Department of Anatomy

1958

)

ACKNOWLEDGMENTS

With sincerity and deep appreciation, the writer
wishes to thank Dr. M. Lois Calhoun, Professor and Head
of the Department of Anatomy, for her untiring and under-
standing assistance in planning and guiding this problem.
The writer is also grateful to Dr. Esther M. Smith for
her very helpful assistance in photography, and other
members of the Anatomy Department for their suggestions
and assistance. He also wishes to express his appreciation
to Leo w. Walker, M. D., and staff of the clinical path-
ology laboratory of St. Lawrence Hospital for their unusual
cooperation. The writer is deeply indebted to the Depart-
ment of Surgery and Medicine for procuring normal animals

used in this investigation.

TABLE OF CONTENTS

INTRODUCTION. . . . . . .
REVIEW OF LITERATURE
Epidermis.
Dermis.
Hair follicle
Sebaceous glands
Sweat glands.
MATERIAL AND METHODS
RESUITS AND DISCUSSION
General.
Specific epidermal layers.
Stratum corneum.
Stratum lucidum.
Stratum granulosum.
Stratum spinosum
Stratum cylindricum
Pigment.
Dermis . . . . . . .
Hairy skin area.
Areas with little or no hair
External auditory meatus.

Metacarpal pad

PAGE

CDWU'l-P‘JEUJTD

14
14
.18
.18
.19
.19

.19
.2O

.2O
.21
.21
.22
.23
.23

Planum nasale.
Lip
Special skin areas
Hair
Follicular folds.
Tactile hairs.
Mm. arrectores pilorum.
Sebaceous glands

Hairy skin areas.

Areas with little or no hair.

Metacarpal pad
External auditory meatus
Upper and lower lip.
Special skin areas
Supracaudal organ
Upper and lower eyelids
Prepuce.
Teat.
Scrotum.
Sweat glands
Saccular apocrine
Coiled apocrine
Coiled merocrine.
Ceruminous glands.

Special body areas . . .

PAGE

Teat. . . . . . . . . . . . . . 3A

Prepuce. . . . . . . . . . . . . 35

Scrotum. . . . . . .. . . . . . . 35

Anal sac and associated glands . . . . . 35

Ear pinna . . . . . . . . . . . . 35

SUMMARY AND CONCLUSIONS. . . . . . . . . . . 37

LITERATURE CITED . . . . . . . . . . . . . 87

FIGURE
A.

B.

LIST OF FIGURES

Body areas from which tissues were taken.

Ear areas from which tissues were taken

LIST OF TABLES

TABLE PAGE
I. The measurement of epidermal and dermal thickness
in the hairy skin areas. . . . . . . . . 15
II. The hair group density in the hairy skin from
oblique sections . . . . . . . . . . . 16
III. Size of mm. arrectores pilorum at the base of

attachment . . . . . . . . . . . . . 28

PLATE

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III.

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LIST OF PLATES

Integumentary papilla in the hairy skin.

An abnormal external auditory meatus.

Dense hairy skin area showing the hair groups.

The dorsal lumbar portion of the hairy skin

The metacarpal pad.

Tubercle in anthelix from outer third of the
external auditory meatus

The lower third of a normal external auditory
meatus

The metacarpal pad showing distribution of
elastic tissue

The nose print area of the planum nasale

Special nerve ending in lip

Subcutis of the foot pad.

Supracaudal gland area

Guard hairs showing the follicular folds

Lip-oblique

A branching arrector pili muscle

Lip-longitudinal

Upper eyelid.

Sweat glands of the scrotum.

Tactile hairs

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66
68

73

PLATE

XX.

XXI.

Small sweat gland emptying into the upper
portion of a hair follicle.

Anal sac and associated glands

ix

PAGE

8A
86

INTRODUCTION

This investigation resulted from a lack of sufficient
information on the normal histology of cat skin and a
request from the department of Surgery and Medicine for
reliable data on the histology of the external auditory
meatus of the cat. The field of dermatopathology relies
on knowledge of the normal, and with the various patho-
logical involvements of the skin and external ear canal of

cats, it is hoped that this work will serve as a reference.

GENERAL REVIEW OF LITERATURE

Relatively little work has been done on the histology
of cat skin. According to Speed (19A1), Backmund (1904)
worked on the embryology of the sweat glands in the cat,
and Teger (1906) reported active sweat glands in the exter-
nal auditory meatus. Stoss (1906) was one of the first to
discuss the histology of cat skin. Frei (1928) studied
the histology of the cat foot pad, while Thuringer (1939)
studied the epidermal mitotic index of this same area.
Trimarchi (1929) reported on the sebaceous and sudoriferous
glands in the nasal vestibule of domestic carnivores.
Varidak (1941) devoted part of his study of domestic animal
skin to that of the cat. Montagna (1949) described the
glands in the external auditory canal, and in 1952 reported
on the epidermis. Tekada (1951) also studied the skin of
the external auditory canal of the cat and other domestic
animals, and Senturia and Liebmann (1956) studied the
factors which may contribute to external ear infections of
the cat. Trautmann and Fiebiger (1957) gave a detailed
description of carnivore skin including some specific infor-
mation on the cat. Daniel and Prichard (1956) described
the arteriovenous anastomoses in the cat and eight other
animals. They found an S shaped anastomosis less complex

and smaller than in most animals studied. Kuntz and

2

Hamilton (1938) found afferent fibers associated with
smaller blood vessels, lamellated end organs in the fore-
limb and foot pad, and a subepidermal plexus made up of
slender nerve strands. Winkelmann (1957) described the
sensory end organ of the hairless skin of the cat. Trautmann
and Fiebiger (1957) found Pacinian corpuscles in the prepuce
of the cat. Kamamura (1957) reported the cytochemical
effect of pilocarpine administration on cat sweat glands,
and described two different types of cells, a superficial
and a basal cell composing the secretory unit of the plantar
foot pad. Dukes (1955) and Marzulli and Callahan (1957)

studied the sweat capacity of the cat.

Epidermis

 

Frei (1928) found that the foot pads of the cat have
a thick epidermis with a superficial horny layer. Wavy
lines separate the cornified cells in the stratun corneum
and the epidermis is pierced by excretory ducts. According

' do not

to Frei ”foot pads that possess functional glands,‘
have typically arranged cornified cells. Stoss (1906)
reported six epidermal strata in the external border of
the nasal septum of the cat. Thuringer (1939) found 2.37
dividing cells per thousand in the cat foot pad. Varidak
(1941) observed that the epidermis of the cat resembles

that of man, but the superficial translucent layer seldom

occurs, while the stratum lucidum is usually present.

Montagna (1952) noted all epidermal layers in the cat

digital pads.

Dermis

Stoss (1936) observed dense, tough connective tissue
fibers in the cat dermis. Frei (1928) reported that the
foot pads of the cat are similar to those of the dog, and
are composed of four rounded pads. The thumb pad is the
weakest, and is absent from the hind feet. He found closely
arranged extremely vascular, short papillae, a less devel-
oped stratum reticulare, and a well developed subcutis.
Trautmann and Fiebiger (1957) described thick layers of

fat in the foot pads of carnivores.

Hair Follicle

 

Trautmann and Fiebiger (1957) found bundles of hair
projecting from common follicular openings in carnivores.
According to these authors three cover hairs composed of
one larger main hair and two smaller hairs usually consti-
tute a group and in the carnivore each group is surrounded
by six to twelve lanugo or wool hairs. Stoss (1936) and
Trautmann and Fiebiger (1957) described nontrabecular
annular sinuses associated with the large tactile hairs of
the cat. These sinuses are smooth walled with a cushion-

like thickening.

\fl

Sebaceous Glands

 

Trautmann and Fiebiger (1957) found sebaceous glands
in all body areas of carnivores except the foot pads and
planum nasale. They reported a ring of sebaceous glands
opening into the tactile hair follices and large sebaceous
glands, "the supracaudal organ," on the dorsal surface of
the cat tail. Stoss (1936) reported many sebaceous glands
on the back, chest, and abdomen of the cat, and found two
to three lobulated sebaceous glands emptying into a single
hair follicle. He also observed large sebaceous glands in
the upper Jaw, prepuce, and proximal dorsal end of the
cat tail, but generally small glands were present in other
body areas. Trautmann and Fiebiger (1957) reported
sebaceous glands independent of hair follicles in the pre—
puce, external auditory meatus, and tarsal glands of the
eye lids in domestic animals. Montagna (1949) described
large clusters of sebaceous glands in the external auditory
meatus and stated that these may or may not be associated
with lanugo hair follicles. He also reported that sebaceous
glands exhibit considerable mitoses particularly at the
periphery of the acini, and contain a moderate amount of
stored lipoids. Trautmann and Fiebiger (1957) observed

sebaceous glands in the teat of the Cat, mare, and bitch.

Sweat Glands

 

Frei (1928) found sweat glands in the foot pads of

carnivores, and Dukes (1955) stated that active sweat

6
glands are confined to the foot pads in the cat, dog, pig,
and ox. Trautmann and Fiebiger (1957) stated that the
prepuce of domestic animals contains prominent tubular
glands. According to these authors well developed sebaceous
and tubular skin glands are found in the scrotal skin of
all domestic animals except the boar, in which they are
scarce and small. Marzulli and Callahan (1957) in testing
the capacity of certain laboratory animals to sweat observed
that the cat did not sweat in hairy skin areas. They
observed an apocrine type of active tubular sweat gland only
in the foot pads of the cat, dog, and rat and in the palms
of the monkey. Stoss (1906) found that sweat glands are
well developed on the lips, plantar pad, ball of the toe
and anus of the cat, but are difficult to demonstrate in
the remaining areas. According to Habel (1958), Ellenberger
and associates reported sweat glands in almost all skin
areas, even extending to the level of the papillae of cover
hairs. Stoss (1906) found that the sweat glands reach as
far as the root of the hair follicle, and that the secretory
ducts are narrow and undulating making up one-third of the
total length of the ducts. Trautmann and Fiebiger (1957)
described coiled secretory tubules in the cat, and Stoss
(1906) reported a tapered excretory duct opening into the
hair follicle and onto the surface of the foot pad. Stoss
concluded that all hair follicles have adjacent sweat

glands which empty into their respective follicle, while

lanugo hairs possess no such glands. According to Speed
(1941),Backmund (1904) concluded that the sweat glands of
the upper and lower Jaw have a special shape and that fetal
hair has a sweat gland but no free openings. Trautmann

and Fiebiger (1957) described apocrine and sebaceous glands
in the anal sac of the cat and tubular and alveolar glands
in the excretory duct of the anal sac.

According to Speed (1941), Teger (1936) observed
active sweat glands in the external auditory meatus of the
cat. Montagna (1949) working on the cat found both
coiled dilated tubular sudoriparous glands and sebaceous
glands opening either into the upper portion of the hair
follicle or directly onto the surface of the external

auditory meatus.

MATERIAL AND METHODS

A total of twenty domestic cats including eight
mature animals, five females and three noncastrated males,
one incomplete immature female, and one immature male were
used for this study. Supplemental sections were secured
from ten other cats. The animals were obtained from the
departments of Physiology and Pharmacology, Surgery and
Medicine, and Anatomy and were sacrificed with a lethal
dose of sodium pentothal. Sections approximately one-half
inch square were taken from twenty-seven body areas as
indicated in Figures A and B. Since Frei (1928) found all
the foot pads to be similar, the metacarpal pad was taken
as a representative example. The tissues were fixed in
formalin-alchol-acetic acid (Lavdowsky‘s mixture, Guyer-
1949), and embedded in'"Tissuemat,fl'according to the methods

of Johnson §£.§l° (1943). Longitudinal and frontal sections

werepueparedvfiifl1a.modified hematoxylin and eosin (Malewitz

and Smith 1955), Weigerts and Van Gieson's connective tissue

stain, Wright's blood stain for mast cells (Belanger gt §l°
1957), and Yang's (1952) method for pigment determination.
Measurements of skin thickness were made in ten represen—

tative body areas. The epidermis was measured in microns

 

l"Tissuemat"--F3sher Scientific Company, Pittsburgh,
Pennsylvania. 8

and sketched on graph paper by projection for future
reference and general comparison. The units of graph paper
were given values according to the calibration of the
microscope. The dermis was measured in four respective
fields at the highest and lowest points. The averages

are given in Table I.

\n

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11.

12.

BODY APEAS FROM WHICH TISSUES

Supraorbital region
Upper eyelid

Lower eyelid

Planum nasale

Upper lip

Lower lip

Dorsal neck
Thoracicolumbar region
Lateral body wall

Ventral abdomen

13.

21.

22A.

223.

WER TAKEN

Tail root
Shoulder

Lateral foreleg
Lateral thigh
Lateral hindleg
Scrotum
Supracaudal gland
Teat (female)
Prepuce

Anal sac

Metacarpal pad

ll

 

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.wa

    

34. 11.1.9:

5

3

12

23-1.
23-2.
24-1.
24-2.

25.

26.
27-1.

27-2.

Figure B

EAR AREAS FROM WHICH TISSUES WERE TAKEN

Apex of pinna

Scapha of pinna

Auditory longitudinal meatus--medial wall
Auditory longitudinal meatus-~lateral wall
Upper one-third of meatus-~level 1

Upper one-third of meatus--level 2

Middle meatus--leve1 1

Lower section near tympanic membrane--level 2
Lower middle meatus--1evel 2

Lower one-third of meatus-~level l

 

 

Figure B. Anterolateral view of cat's ear

\OOO'\10\\N 4:me

Cut edge of tragus
Rostral border

Caudal border

Anthelix (tubercle of)
Posterior auricular sulcus
Antitragus

Anterior auricular sulcus
Plica antitragica
Incisure intertragica
Scapha

Longitudinal ear folds
Transverse folds

 

1.53 'H'BJ

 

 

Figure B. Anterolateral view of cat's ear
1. Cut edge of tragus
2. Rostral border
3. Caudal border
4. Anthelix (tubercle of)
5. ~Posterior auricular sulcus
6. Antitragus
7. Anterior auricular sulcus
8. Plica antitragica
9. Incisure intertragica
10. Scapha
ll. Longitudinal ear folds
l2. Transverse folds

13

RESULTS AND DISCUSSION
I. GENERAL

From a comparative viewpoint most investigators have
assumed the skin of the cat to be similar to the skin of
the dog. This is essentially true but certain apparent
differences will be pointed out in the following discussion.
Due to certain area limitations and specialization, the ten
general body regions shown in Table I were selected as most
typical for an over-all picture.

The thickest areas are found on the dorsal neck,
lumban and sacral regions. The thinnest areas are on the
lateral sides of the lower hind leg, thigh, and lower fore-
leg. Generally the thickness decreases from dorsal to
ventral on the trunk, and from proximal to distal on both
front and hind limbs. The maximum skin thickness is 1905
microns in the dorsal neck region and a minimum of 374
microns on the lower lateral side of the hind leg.

The epidermis is thin in all hairy areas, usually
measuring between twenty and thirty microns, with a range
from twelve to forty-five microns. According to Lovell
and Getty (1957), the average epidermal thickness in the
hairy skin of mongrel dogs is thirty to forty microns.

Webb and Calhoun (1954) reported the thinnest epidermis in

14

‘A'llll'l'I It'll II"
I 'I‘

15

mongrel dogs to be 26.5 microns in the sternal region.
In the present investigation twenty-five microns is con-
sidered an average epidermal thickness in the cat. One
may assume that the epidermis in mongrel dogs is generally
thicker than that of the cat in the hairy skin areas. The
epidermis of the prepuce, scrotum, and similar specialized.
areas of the cat ranged from seventeen to sixty microns,
while similar areas in mongrel dogs measured sixty-seven
to ninety microns (Webb and Calhoun 1954).
Small hairless knoblike enlargements in the hairy
skin area of mongrel dogs have been referred to as epidermal
papillae by Lovell and Getty (1957). Since both the
dermis and epidermis are involved in this structure the
term integumentary papillae seems more appropriate (Plate I).
The epidermis of these integumentary papillae in the cat
is thicker than the epidermis of most hairy areas. Occasional
epidermal thickness to 100 microns may be seen in the anal
sac lumen. The thickest epidermis is found in the digital
pads and planum nasale and measures 900 microns compared
to 1,800 microns seen in mongrel dogs (Lovell and Getty 1957).
The epidermis of the planum nasale exhibits prominent
ridges which form the basis for the nose print technique

similar to human finger printing methods (Plate IX).

16

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17
II. SPECIFIC EPIDERMAL LAYERS

The nonhairy skin of the cat consists of five distinct
epidermal layers: stratum corneum, stratum lucidum, stratum
granulosum, stratum spinosum, and stratum cylindricum. In

hairy skin areas, the stratum lucidum is not usually found.

Stratum Corneum

 

The stratum corneum is present in most body areas.
This is in contrast to the findings of Varidak (1941), who
stated that the superficial translucent stratum corneum is
usually absent. In hairy skin, it varies from three to
twenty microns. In certain areas such as the integumentary
papillae, the stratum corneum may be thicker. It is best
developed in the digital pads and planum nasale and ranges
from fifteen to thirty-five microns. In the anal sac gland
and lip, the stratum corneum is well developed, although
not as thick and prominent as in the metacarpal pad and
planum nasale. In the external auditory meatus the stratum
corneum and related layers may become hyperplastic and con-
tribute to a change in the general morphology of the skin
of that area. It increases in thickness and in certain
instances covers the openings of sebaceous and ceruminous
glands that open upon the surface. The epidermal thickness may
increase as much as three to four times forming inter-
papillary pegs. The cells of the epidermis appear to

migrate into the dermis and invest the sebaceous andcerumin—

ous glands (Plate II).

18

The'Stratum;Luridum

 

The stratum lucidum is best developed in the metacar-
pal pad where the thickness ranges from twenty-eight to
forty microns. It is less developed in the planum nasale
and anal sac and is absent from almost all hairy skin areas.
It is not present in the external auditory meatus. These
findings are directly opposed to those of Varidak (1941) who
stated that the stratum lucidum is generally present in most

body area

Stratum‘GranulosEm

 

The stratum granulosum.consists of one or two layers
and is present in most of the hairy and nonhairy skin areas.
The thickest stratum granulosum is in the metacarpal pad
and consists of 4 to 8 cell layers. In the planum.nasale
there are usually 3 to 4 layers of cells, which contain
dark cytoplasmic granules (Plate IX). These granules are

very prominent in the teat and scrotum.

S tr atum Spin‘osum

 

The stratum spinosum is present in all sections of
hairy and nonhairy skin. In hairy skin, it averages from
1 to 2 layers. Where there are integumentary papillae with
a thick cornified epidermis, as many as 5 layers are not
uncommon. The tonofibrils (intercellular bridges) are
not as prominent in the hairy as in the nonhairy skin

(Plate X). In the nonhairy metacarpal pads, planum nasale,

l9
and the less hairy hyperplastic external auditory meatus
the stratum spinosum contains the greatest number of
layers. As many as 38 cell layers are sometimes observed
(Plates II, V, and IX). The stratum spinosum of the teat,
scrotum, prepuce and portions of the external auditory

canal exhibit a loose nonuniform layer.

Stratum Cylindricum

 

The stratum cylindricum is present in all sections
studied and is composed of one layer of cells, which
usually is oriented perpendicular to the epidermis. Few
mitotic figures are present. These cells stain slightly
darker than the cells of the other epidermal layers and
generally appear tall and columnar in shape. This is not
(always true in the external auditory canal, teat, and

scrotum, where the epidermis may be less stratified.

III. PIGMENT

The pigment concentration varies considerably according
to the body area in the cat. With reference to the ten hairy
skin areas illustrated in Figure 4 (areas 3 and 9 to l7),there
is little relationship of pigment to hair color. In the hairy
areas the skin is usually devoid of pigment and the color
of the hair coat is concentrated in the individual hairs.

The darker skin of the lip, digital pads, and planum nasale

23
usually contains large amounts of pigment in the epidermis
and little or no pigment in the dermis. A small amount of
pigment is seen in the epidermis of the external auditory
canal, and ear pinna. Specialized areas such as the
prepuce, scrotum, anal sac, and teat exhibit pigment in
the epidermis. Chromatophores are occasionally observed in

the dermis of the scrotum.

IV. DERMIS

The dermis is composed of collagenous, elastic, and
reticular fibers, nerve components, and blood vessels.
Nerve structures resembling those described by Winkelmann
(1957) are present in the lip, planum nasale, and metacarpal
pads. Plate X shows a special nerve ending in the cat lip,
and Plate XI illustrates a Pacinian corpuscle in the deep
portion of the metacarpal pad. Large nerve trunks are
observed crossing the blood sinuses in tactile hairs. Large
and small nerve trunks are seen throughout the dermis in

the hairy skin, and are usually associated with blood vessels.

Hairy Skin Area

 

The hairy skin is usually characterized by a very
indefinite division between the stratum papillare and the
stratum reticulare. The stratum papillare is composed of
fine collagenous fibers which usually are parallel to the

epidermis (Plate III). These fibers appear more uniform

21

than those of the stratum reticulare. The elastic fibers

of this layer form a fine interlacing network, but occasion-
ally single fibers are present. The fibers of the papillary
layer appear to interlace near the dermal-epidermal Junction.
These observations agree with those of Dick (1947) and
Odland (1950)..

The stratum reticulare is characterized by large
densely arranged collagenous fibers which are approximately
three times larger than the fibers of the stratum papillare.
These form large bundles extending in all directions (Plate
IV). These fibers encircle hair follicles throughout the
reticular layer, and usually disappear at the Junction with
the subcutis giving way to adipose tissue. The elastic
fibers increase in number, extend in all directions and also
encircle the hair follicles. Elastic fibers appear to
Vadhere to the side of collagenous fibers in the reticular
layer and are increasingly abundant near the attachment of
the arrector pili muscle. In areas where the skin is most
flexible, such as the dorsal neck, scapular region and
lateral upper forelimb, collagenous bundles are smaller

and more loosely arrange.

AreaS'With:Little'or'N0'Hair

fflmenonhairy areas are the planum nasale and the
metacarpal pad. The lip and external auditory meatus have
little or no hair present. Since the dermal strata vary,

depending on the area, a regional discussion seems more

appropriate.

22

External auditory meatus. Both dermal layers are

 

present in the external auditory canal with the fiber con~
tour determined by folds in the skin and the number of
sebaceous and ceruminous glands. The skin of the external
auditory meatus exhibits large and small folds in the outer
and middle divisions. Small elastic and collagenous fibers
surround the sebaceous and ceruminous glands immediately
beneath the epidermis (Plate VII). This layer is referred
to as the stratum papillare in keeping with the size of
fibers and description of skin in other areas, but in hyper—
plasia a more definite papillary layer is formed (Plate II).
The fibers beneath the papillary layer are large and
resemble the reticular layer in other areas, with the excep-
tion of being extremely dense. These fibers fuse with

the perichondrium of the elastic cartilage. The elastic
fibers of the lower meatus appear larger, more numerous,

and extend parallelto the epidermis. The folded areas
usually possess a fat-laden central portion as illustrated
in Plate VI, which occasionally contains ceruminous glands.
These folds have more surface area resulting in less

crowding of the dermal elements.

Metacarpal pad. The dermis has very prominent dermal

 

papillae and interpapillary epithelial pegs which expand
with weight. The dermis is characterized by a definite
division between the stratum papillare and stratum reticul-

are. Frei (1928) reported that short dermal papillae

23

contained a large amount of blood vessels. In this investi-
gation no)significantdifTerences were noted in any of the
papillae studied (Plate V). The finding of closely arranged
papillae and a less developed stratum reticulare agrees

with the observation of Frei (1928). The subcutis is com-
posed of thick bands of collagenous fibers and abundant
smaller.elastic fibers which interweave and enclose the
panniculus adiposus (Plates V and VIII). Plate VIII shows
the Junction between the subcutis and hairy dermis of the
foot pad. Large number of elastic fibers separate the two
areas. The arrangement of these layers concurs with the

description of carnivores byTTautmannznmiFflebiger (1957).

Planum nasale. The planum nasale has a thick well

 

developed stratum reticulare. The fibers appear unusually
large as compared with the small fibers of the stratum
papillare (Plate IX). The fibers form a very distinct pap—
illary body. Nerve structures resembling those described

by Winkelmann (1957) are present.

Lip. The dermis of the lip is composed of very little
connective tissue as compared with other less hairy skin
structures. Plates XIV, XVI, and XIX illustrate the sparse
amount of connective tissue in relation to the other dermal
elements. The connective tissue fibers are prominent only
immediately beneath the epidermis. No distinctive stratum

papillare and stratum reticulare are observed.

Special_§kinwAreas

 

Teat, scrotum, prepuce, and eyelid. The connective

 

 

tissue fibers of the teat are very dense as compared with
other skin areas. A distinct stratum.papillare and stratum
reticulareare present (Plate XXII). The numerous elastic
and collagenous fibers run both parallel and horizontal to
the epidermus. The dermis of the prepuce and scrotum is
composed of a coarse fiber network. No distinctive stratum
papillare or stratum reticulare are present in the scrotum
but the parietallayer of the prepuce exhibits a papillary
body. The connective tissue of the eyelid is composed of
many collagenous and elastic fibers (Plate XVII). The
contour of these fibers is interrupted by the eye lashes
and tarsal glands. No distinctive dermal layers are
observed but the fibers near the epidermis of the eye
lashes appear smaller than the fibers of the deeper layers.
This observation agrees with that of Trautmann and Fiebiger

(1957) on the eyelid in domestic animals.

V. HAIR

The hair of the cat is arranged in clusters of two,
three, four, and five groups around a large central guard
hair with two and three being more common on the dorsal
aspect of the body (Plates III and IV). Clusters of four
and five when present usually occur in the ventral and lower

extremities. Table II illustrates the distribution of hair

25

.mpczoo m>

H1

b V P I | r 7 D I

.9? a»? mi

’44

am mo mwwhm>w no musmmmsmmp mpzwfim zoom *

I ' r ( ([)

. \ \ \ Q \ .

 

s.HH s.me s.me .sH m.ma m.mH omoso>a

Hosana

m.oa me be me me me we we EH em woaoqam
Haywood

H.8H 0H me we we EH me EH EH EH swans
Hmhmpwq
m.oH we we ma ea we we we we we woaosom
Hmmmpmq

m.sH ea me me me ea se me 4H NH sooasonm
m.HH m Ha o NH me He 0H 0H 0H ooom
Hess

H.me Ha Ha me me me He me me me soEoona
ngpzo>

H.me He me me me me as :4 NH ma ansfim
m.m m m Ha m m m oH m ma sensed
Hmmwom

m.oH m m HH Ha Ha AH me me HA sooz
manmeEH mepom

mum owsso>< Sate 21:2. warm m--m zrnm . ma-o . muuo wrum,. zwna

’ I r(

I I r 'r '

ITINUH

*mZOHBomm ZHMm MDdHHmO 2H mMBmzHQQHE mm<DGm mmm MEHmZmQ mbomw mHgm .HH mQMdE

26
in the nine body areas. While there are too few animals
to form any definite conclusion, these data suggest that
the hair might be less dense in males than in females. Each
lateral group usually contains three primary hairs surrounded
by six to twelve lanugo hairs (Plate III). These findings
agree with the description given by Trautmann and Fiebiger
(1957) for carnivores. From twelve to twenty hairs are
seen diverging;fiom a common opening. 0n oblique sections
of the dorsal aspect of the hairy skin areas there are eight
or nine groups of hairs per square millimeter. Toward the
ventral surface and the lower extremities this number in-
creases to twelve or sixteen groups per square millimeter.
The hair arrangement is essentially the same over the entire
body with the exception of the dorsal supracaudal area of
the tail where the array is less complex (Plate XII). These
hairs of the tail appear larger than those of other areas
of the skin. The supracaudal area does not extend the
entire dorsal length of the tail but is restricted to a
small central area as indicated on Figure A. This is
similar to the supracaudal area in the dog, described by

Lovell and Getty (1957).

Folliculaerglds

 

Follicular folds first described by Goldsberry (1955) in
the cow are present in the upper portion of the guard hair folli-
cle only (Plate XIII). The folds appear to be undulations of

the stratum corneum. Cells resembling the stratum spinosum

27
are observed beneath this layer. Goldsberry (1955) reported
from ten to twenty-five follicular folds in the cow. From
five to ten folds are observed in the follicle of the cat.
Because of the opening of the sebaceous glands into the
hair follicle Just proximal to these folds, it is possible
they bear some relation to the expulsion of oil to the sur-
face. Future research may show that these folds are present
in, and have specific numbers and characteristics for each

species of mammal.

Tactile Hairs

 

The tactile or large sinus hairs (vibrissae) contain
a cushion like thickening of connective tissue surrounding a
large smooth walled annular blood sinus. This sinus is
usually filled with blood and measures approximately 900
microns in diameter (Plates XIV and XIX). Striated muscle

fibers are associated with tactile hairs (Plate XVI).

Mm: Arrectores~Pilorum

 

The arrectores pilorum are bundles of smooth muscle
present in all sections of the hairy skin. They are most
highly developed on the dorsal lumbar, sacral, and tail
regions. They measure as much as 150 to 220 microns in
diameter at the base of the attachment to the follicle
(Table III). These muscles may be seen branching as they
approach the epidermis (Plate XV). The smallest muscles are

found in the lateral fore and hindleg.The muscle attaches to

28
the lower portion of the guard hair follicle and appears

to extend to the adJacent hair clusters.

 

TABLE III. ARRECTORES PILORUM MUSCLES*
Dorsal Neck 29-43 Tail Foot 40-80
Dorsal Lumbar 153-200 Shoulder 23-45

Supracaudal Area 153-220 Lateral Foreleg 25-30

Flank 25-60 Lateral Thigh 30-60
Ventral Abdomen 25-35 Lateral Hindleg 25-30
1" fifig #11 :L" ffi *1 afiii'l}:

 

 

 

w a

*Range of size in microns at the base of attachment to
the follicle.

VI. SEBACEOUS GLANDS

The sebaceous glands show a characteristic simple
alveolar structure. Differences in size of these glands

are very striking in certain areas.

Hairy Skfn Areas

 

The diameter of sebaceous glands in the general hairy
skin area ranged from 20 to 75 microns. These empty into
the upper portion of the hair follicles around which they
are clustered. This is in agreement with Stoss (1906) who
found two to three lobulated sebaceous glands surrounding
the follicle throughout general body areas. Plate IV
illustrates the general size and arrangement of sebaceous

glands throughout the hairy skin area.

29
Areas With Little or No Hair

Metararpal pad. No sebaceous glands are found in

 

the metacarpal pad. This is similar to the dog as described

by Lovell and Getty (1957) and Webb and Calhoun (1954).

External auditory meatus. There are generally large

 

clusters of sebaceous glands in the outer third of the
meatus, where the cartilage has infringed on the dermis to
form ridges or tubercles resulting in more surface area
(Plate VI). No mitotic figures are observed contrary to the
report by Montagna (1949). The number of sebaceous glands
depends on their location in the meatus. In the outer

third there are one to two large clusters per square
millimeter in the areas with ridges and tubercles. In the
middle meatus, this number is slightly increased, and dis-
tinctive crowding is seen in the lower third of the canal
nearest the tympanic membrane. Although the largest sebac-
eous clusters in the external auditory canal measure approx-
imately 300 microns in diameter, a variety of sizes may

occur. A similar description was given by Montagna (1949)

in the cat, and in the dog by Nielsen (1953).

Upperand lower lip. The sebaceous glands of the

 

lip are large measuring 500 to 800 microns. The larger
glands have a somewhat elongated shape (Plates XVI

and XIV). The lip also has smaller sebaceous glands associ-
ated with the tactile hairs. They are approximately the same

size as the sebaceous glands of the hairy skin and are located

around the upper portion of the large hair (Plate XIX).

Special Skin;Areas

 

Supracaudal organ. The sebaceous glands of the supra-

 

caudal organ are approximately 700 microns in diameter.
These are large oval clusters located on the proximal dorsal
aspect of the tall. These sebaceous glands usually stain
slightly darker than the sebaceous glands in other areas
(Plate XII). All other areas of the tail exhibit small

sebaceous glands similar to those of other hairy skin.

The upper and lower eyelids. The sebaceous glands

 

of the upper eyelid are larger and more highly developed
than those of the lower lid. In the upper eyelid the tarsal
glands (Meibomian glands) are arranged in a linear series
along the posterior portion. They are oval shaped clusters

measuring 450 microns in diameter (Plate XVII).

Prepuce. The sebaceous glands of the prepuce are
usually large, ranging in diameter from 100 to 200 microns.

They are usually associated with hair follicles in this area.

Teat. The sebaceous glands of the teat are few and
occur in isolated groups resembling the sebaceous glands
of the hairy skin area in size. Sebaceous glands previously

were reported in the teat by Trautmann and Fiebiger (1957).

Scrotum. The sebaceous glands of the scrotum although
more dense and slightly smaller, resemble those of the

prepuce.

31
VII. SWEAT GLANDS

In this investigation sweat glands are found in all
sections studied with the exception of the planum nasale.
Although an intensive search of this area has been made for
glands which might be the source of the moisture usually
present on the surface, none are seen. This agrees with
the work of Lovell and Getty (1957) and Webb and Calhoun
(1954) on mongrel dogs. Sweat glands of the cat exhibit
two physiological types. They are saccular and coiled apo-
crine glands occurring over the general body areas and
coiled merocrine glands of the metacarpal pads. These
resemble those described by Stoss (1906) and Trautmann and
Fiebiger (1957) but there is some controversy as to their
distribution. In contrast to the above findings, Trautmann
and Fiebiger (1957) reported "poorly developed glands of
the cat are present only" in the oral region, anus,lower

Jaw, and foot pads.

Saccular Apocrine

fa wfi fl

 

Both small and large saccular apocrine sweat glands
occur in the cat. In the hairy skin areas the glands are
generally small, with a sac shaped secretory portion. The
excretory unit opens into the upper portion of the hair
follicle in agreement with Stoss (1906) (Plate XX). These
glands are composed of low cuboidal epithelium, a reticular

tissue framework and a thin layer of smooth muscle. With

I

32
reference to sweat capacity, Marzulli and Callahan (1957)
found that the cat did not sweat in any area except the
foot pad. It appears that the small sweat glands of the
hairy skin area function very little or are completely non-
functional. The secretory unit of these glands measures
between fifteen and thirty-five microns in diameter. The
excretory portion can not always be followed but it is
much smaller than the secretory unit. The sweat glands
occasionally pierce the arrector pili muscles as illustrated
in Plate IV.

The larger saccular sweat glands are found in the
supracaudal organ and scrotum ranging from 45 to 110 microns
in diameter (Plates XII and XVIII). The larger saccular
apocrine glands are essentially the same as the smaller.

glands except for taller epithelium.

Coiled Apocrine

 

Large coiled apocrine sweat glands occur in the upper
and lower 1145 eyelids, anal sac, and prepuce. Saccular
apocrine glands are usually found in combination with the
coiled glands in most of these sections (Plates XXI and
XVII). These glands are large resembling the saccular glands
of the supracaudal organ and scrotum. In the upper and
lower lip the glands are so extensively coiled that Backmund
in 1904 (Speed 1941) concluded that these glands had a
special shape. In contrast to these findings in the cat,

Webb and Calhoun (1954) reported only coiled apocrine sweat

33
glands in the lip of mongrel dogs. The sweat glands of the

eyelids are less coiled than those of the lips. Nielsen
(1953) described large coiled apocrine sweat glands over
the entire skin of various breedsof dogs and Webb and
Calhoun (1954) reported similar findings in mongrel dogs.
In the cat the glands of the general body area are com-
paratively small and are usually saccular. One may assume
that the sweat glands of dogs and cats are generally the
same in structure but may differ in certain regions of the
body. The large sweat glands of the prepuce are associated
with the hair follicles. These glands have tall columnar
cells, each bearing a very distinct apex protruding into
the lumen of the glands. Similar morphological observations
were reported by Nielsen (1953) for the glands of canine

skin.

Coiled Merocrine

 

Small merocrine sweat glands are situated in the
subcutaneous fatty tissue of the metacarpal pads (Plate V).
These glands are extensively coiled and are similar to
those reported for the foot pad of the canine by Nielsen
(1953). Merocrine sweat glands were found only in the
foot pad in contrast to the apocrine type in all other

sections of the skin.

VIII. CERUMINOUS GLANDS

The ceruminous glands are found throughout the
external auditory meatus and open upon the surface of the
canal or into hair follicles. These glands increase in
number in the lower third of the meatus. They are coiled
dilated tubular glands similar in structure but larger than
sweat glands, measuring sixty-five to eighty-five microns
(Plate VII). The epithelium is tall columnar. The
ceruminous glands are more numerous than the sweat glands.
A similar condition «guidescribed by Nielsen (1953) in the
canine. Under pathological conditions the ceruminous
glands may increase in size five to six times and become

filled with cellular debris (Plate II).

IX. SPECIAL BODY AREAS

meet
The teat of the cat is composed of a hairless external
surface with a moderate epidermal thickness, and epidermal
pegs. The dermis possesses an abundant amount of collagen-
ous and elastic fibers with dermal papillae. The fiber
arrangement is both parallel and horizontal to the epidermis.
Situated within these fibers are bundles of smooth muscles
and clusters of sebaceous glands. There are seldom more

than three_or four milk ducts present in any one histological

section but the cat teat may contain as many as seven

(Plate XXII).

Prepuce

The prepuce is covered with a thin layer of strati-
fied squamous epithelium resembling that of other body
areas. The epithelium lining the prepuce is composed of a
layer of stratified squamous epithelium which is usually
thicker than that of the general body area, and forms
epidermal pegs. The dermal portion is comprised of a large
amount of collagenous and elastic fibers and skeletal
muscle. Trautmann and Fiebiger (1957) observed skeletal
muscle in all domestic animals except the horse and cat.
The sebaceous and sweat glands are large and associated

with the hair follicles.

Scrotum

The epithelium of the scrotum is less cornified than
that of other body areas. The cell layers appear loose and
irregular in shape compared to the epidermis in other areas.
The connective tissue is very coarse with little distinction
between papillary and reticular layers. The sweat and
sebaceous glands are large and are associated with the hair

follicles (Plate XVIII).

 

The Anal Sac and Associated Glands
The anal sac is a small spherical structure found

lateroventrad to the anus. It is a sacculation of skin

36
into which sebaceous and coiled apocrine sweat glands open.
The large columnar lined sweat glands surround the strati-
fied squamous epithelial lined sac (Plate XXl), and secrete
fluid into the lumen. The sebaceous glands form a large
cluster and empty into the sac. The underlying connective
tissue contains collagenous and elastic fibers which
extend parallel to the epidermis and includes some skeletal
muscle. A similar description of the anal sac of the dog

was given by Nielsen (1953), and Montagna and Parks (1948).

Ear Pinna

 

The ear pinna is composed of a central core of elastic
cartilage and skeletal muscle covered on both sides by a layer
of skin. The skin is very thin, has dense connective
tissue characterized by a very indefinite division between
_the fibers of the stratum reticulare. The skin increases
in thickness from the tip of the pinna to the opening of
the external auditory canal. The skin of both surfaces
contains sweat and sebaceous glands with short, crowded,
excretory and secretory units due to the presence of the
cartilaginous septum. The hair distribution on the convex
side is usually dense similar to other hairy skin areas.

The concave surface has very sparse and fine hair except
toward the rostral border. Occasionally, single follicles
are observed resembling those of the external auditory

canal.

SUMMARY AND CONCLUSION

Skin specimens were studied from twenty-seven body
areas including the external auditory canal. Five mature
females, three noncastrated mature males, one incomplete

female, and one immature male were studied. Selected skin

sections were taken from ten other cats.

Hairy_SkrnrArea

 

The thickest areas are the dorsal neck, lumbar, and
sacral regions. The thinnest areas are the lateral hindleg,
thigh, and lower foreleg. The skin thickness decreases
from dorsal to ventral and proximal to distal, with the maxi-
mum being 1905 and minimum 374 microns. The epidermis in the
hairy skin averages 20 to 30 microns. Microscopic hairless

integumentary papillae are found in the hairy skin.

Areas with Little or No Hair

 

The thickest epidermis 900 microns is observed in
the metacarpal pad, although that of the planum nasale and
lip are well developed. Specialized epidermal areas usually
rangefrom 17 to 60 microns but an occasional thickness of

133 microns is observed in the anal sac lumen.

Sex and Age Difference s

 

The only sex difference is observed in the fat layer

of the skin. This layer in females appears better developed
37

38
than in males. The skin of the one immature cat is thinner
and possesses a greater amount of connective tissue. These
tissue fibers are smaller and appear more dense than the
mature specimens. The microscopic hair population in
oblique sections is more dense per square millimeter in the

immature animal than the mature specimens.

Specific Epidermal Layers

 

The epidermis of the cat skin is usually composed
of four layers, the stratum lucidum being absent from

most hairy skin. The stratum corneum is usually present

 

in all areas measuring 3 to 20 microns in hairy skin and
15 to 35 microns in nonhairy skin. This layer may become
thickened in the external auditory meatus contributing to

an abnormal condition. The stratum lucidum is usually

 

absent in all hairy skin, ear canal, and lip, but is
present in the anal sac,foot pads,and planum nasale. The

stratum granulosum consisting of one or two layers is

 

present in most body areas. The thickest layer is found
in the metacarpal pad with 4 to 8 layers and the planum
nasale with 3 to 4 layers. The teat and scrotum exhibit
very prominent cytoplasmic granules in this layer. The

stratum spinosum is always present showing the greatest

 

variation in the number of cell layers. These layers range
from one to two in hairy skin to as many as 38 in the non-
hairy foot pad. Tonofibrils are more prominent in thick

nonhairy than in hairy areas. The stratum cylindricum is

 

39

composed of one layer of darker staining cells. Few mitotic
figures are present. These cells usually appear tall
columnar but variations in shape may occur where the epi-
dermis is less stratified. Epidermal pegging is present

in the lip, planum nasale, metacarpal pad, teat, and prepuce.

Pigment

The skin pigment is concentrated in the epidermal
layers in areas with little or no hair and in individual
hairs in the hairy skin. No pigment is found in the dermis
or epidermis in the hairy skin, but is found in the epi-
dermis of the teat, scrotum, prepuce, and anal sac.
Occasional chromatophores are observed in the dermis of

the scrotum.

Dermis

Hairy skin. The papillary layer is composed of fine

 

collagenous fibers which usually run parallel to the epi-
dermis and appear more uniform than the fibers of the
stratum reticulare. Elastic fibers form a fine interlacing
network with single fibers occasionally observed. The

stratum reticulare possesses dense collagenous fibers

 

approximately three times larger than fibers of the
stratum papillare. These fibers form bundles, encircle
hair follicles and extend in all directions. Elastic
fibers increase, anastomose and occasionally appear to

adhere to the sides of large collagenous fibers. Elastic

40
fibers are more abundant where arrector pili muscles attach
and where the skin is more flexible. No dermal papillae
are observed in the hairy skin areas. The pinna is char-

acterized by two thin skinned surfaces separated by an

elastic cartilage support.

Areaegwith little or no hair. The external apditegy

fifiv

 

 

meatus exhibits both layers of the dermis but the fiber
arrangement may be altered by the size and number of glands
present in the three divisions of the external auditory
canal. The stratum papillare shows the same general mor-
phology as in other areas. The fibers are small and extend
in the same manner as described in the hairy skin. The
stratum reticulare becomes very dense as it fuses with

the perichondrium of the elastic cartilage. Elastic fibers
appear larger and more numerous in the lower third of the

' meatus. Few fibers are observed in sections showing hyper-

plasia. The metacarpal pad has a papillary layer with

 

closely arranged prominent dermal papillae, and a less
developed reticular layer is present. Thick collagenous
and elastic fibers comprise the well developed subcutis.

The planum nasale has thick well developed collagenous

 

and elastic fibers. The fibers of the papillary layer are
very small forming a distinct papillary body. The stratum
reticulare is composed of unusually large fibers as compared
with the papillary layer. Specialized nerve structures are
present in the lip, planum nasale, and metacarpal pad. The

lip has very sparse connective tissue.

41

Hair

 

The hair of the cat occurs in clusters of two, three,
four, or five grrnge bunched. around a central guard hair.
Groups of two and three are most common on the dorsal, back,
and tail region; and four and five on the ventral surface
and lower extremities. Twelve to twenty hairs diverge from
a common opening. Hair group density is less per milli-
meter on the dorsal surface and increases in density
toward the ventral surfaces and lower extremities. Follic-
ular folds first described by Goldsberry (1955) are present

only in the upper portion of the guard hair follicle.

Mm. Arrectores Pilorum

 

These muscles are the most highly developed on the
dorsal lumbar, sacral, and tail regions. This seems to
be correlated with the elevation of hair in these regions.
In skin where little or no hair elevation occurs the
muscles are less developed as on the dorsal neck, ventral

abdomen, and lower extremities.

 

Sebaceous Glands

HairyFskin areas. Sebaceous glands ranging from

 

23 to 75 microns in diameter form clusters and empty into
the upper portion of the hair follicle in the general body
areas. In the glands of the supracaudal organ are excep-

tionally large measuring approximately 800 microns.

Areas with little or no hair. The sebaceous glands of

the lip are also large measuring 500 to 800 microns. The

42
glands of the lip are usually elongated while the supracaudal
glands are oval. Small sebaceous glands are associated with
the tactile hairs. No sebaceous glands are found in the
planum nasale or metacarpal pads._ Sebaceous glands of the
external auditory meatus and upper eyelid measure from 200
to 450 microns in diameter.' The tarsal glands are usually
consistent in size but the glands of the external auditory
meatus vary in size. Sebaceous glands of 100 to 200 microns
in diameter are associated with hair follicles in the prepuce
and scrotum. Sebaceous glands of the external auditory
meatus, teat, and the tarsal glands may occur independently

of hair follicles.

Sweat Glands

 

 

Sweat glands are found in all sections studied with
the exception of the planum nasale. They exhibit two
physiological types (1) saccular and coiled apocrine glands
occurring over the general body areas, and (2) coiled
merocrine glands of the metacarpal pad. Both large and
small saccular glands occur in the hairy skin areas, supra-
caudal organ, and scrotum. Both saccular and coiled
apocrine glands are found in the upper and lower lip, eye-

lids, anal sac, and prepuce. Ceruminous glands are found

 

throughout the external auditory meatus.

43

PLATE I

Oblique section through an integumentary papillae

in the hairy skin. H. and E. 280x.

1.

2.

Integumentary papillae.

Numerous follicles per group.
Indefinite stratum papillae and stratum
reticulare.

Large guard or central hair.

Lateral and lanugo hairs.

Sebaceous glands.

N a“ nut—- -~——. *- _..

 

 

PLATE II

Section from lower third of external auditory meatus

showing hyperplastic epidermis, distended ceruminous

glands, calcium deposits, and degenerate sebaceous

glands.
H. and E.

l.

2
3
4.
5

Plate VII shows the normal in the same area.

250x.

Stratum spinosum.

Degenerate sebaceous glands.
Modified ceruminous glands.
Calcium deposits.

Stratum cornium.

 

. o
”.

3
b”
,J

i" ‘
aux:

”O-
C
o-
" .
1L3

46

 

47

PLATE III

A section from the dense hairy skin area of

the lateral lower leg. H. and E. 280X.

[U

mmtw

Epidermis.

Stratum papillare.

Stratum reticulare.

Lanugo hair.

Large connective tissue fibers.

Typical hair group showing three primary
hairs and twelve lanugo hairs.

Four to five groups around a central

guard hair.

 

48

 

PLATE IV

Section through the dorsal lumbar region representative

of the hairy skin of the entire back. Note the size of the

sebaceous glands, also sweat gland traversing the

arrector pili muscle. H. and E. 360x.

1.

2.

Large guard hair flanked by.two clusters or groups.
Sebaceous glands.

Large bundles of collagenous fibers in the
stratum reticulare.

Lateral follicle groups.

Sweat gland extending through the arrector
pili muscle.

Collagenous fibers parallel to the epidermis.

Sweat duct at the edge of a lateral group.

 

 

SO

51

PLATE v

Section through the metacarpal pad. H. and E. 11X.

1.

[—1
O

11.

12.

\0 (D4 O\\)‘| JZ‘LJO R3

Stratum corneum.

Stratum,lucidum.

Stratum granulosum.

Stratum spinosum.

Stratum cylindricum.

Stratum papillare.

Stratum reticulare.

Merocrine sweat glands.
Panniculus adiposus.

Sweat gland ducts opening upon the surface
of foot pad.

Interpapillary or epidermal pegs.

Dermal papillae..

 

\fl

M

l)

52

 

PLATE VI

Section of a tubercle in anthelix showing the large
less densely arranged sebaceous glands and fat-laden
central portion representative of all ear folds. Com-
pare density of sebaceous glands with Plate VII.
H. and E. 183x.

1. Sebaceous glands.

2. Adipose tissue.

3. Collagenous and elastic fibers.

 

 

\TI

\_ 5‘1

PLATE VII

Section through the lower third of the external auditory
meatus showing the normal condition of the area as
compared with Plate II in the same region. Note.the
difference in the thickness of epidermis, sebace6us
glands, and the ceruminous glands. H. and E.
242X.

1. Epidermis

2. Sebaceous glands.

3. Ceruminous glands.

4. Sebaceous glands opening upon surface of

external auditory meatus.

 

56

 

PLATE VIII

Section of the metacarpal pad showing the Junction of

the hairy and nonhairy subcutis, and distribution of

elastic tissue. Weigert's and Van Gieson‘s connective

tissue stain. 256X.

1.

.t L» m

\J'l

Elastic tissue (black).

Apocrine sweat glands.

Dermis of hairy and nonhairy Junction.
Coiled merocrine sweat glands.
Panniculus adiposus.

Groups of hair follicles.

 

 

 

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V)

s n. : 3
.110“... .\\
o a” in. v.0 . § \

.1 :. .1... :.
. I '.b .3. . Ab \. - 49d... .Y.
.4. .1... . .\ a.‘ .\\\
O
‘

All

\

I
a, . ~.-
‘4 .
. .\

‘

 

PLATE IX

Section through the nose print area of the planum
nasale. Weigert Van Gieson stain, 220X.
l. Stratum corneum.
2. Stratum spinosum.
3. Large collagenous fibers of the reticular
layer.
4. Stratum papillare.

5. Stratum granulosum with prominent cytoplasmic

granules.

\

o .
.‘
Ikko‘... . .
. T Q i
. ’ r ‘i c

4 y

.3). .uAHD. p. a

«a ._ ._
..\\1\ - W\ a v .

3C. .

.0

 

60

 

61

PLATE X

Special nerve ending in the lip of the cat.
E. 1533X.

1. Epithelium.

2. Nerve ending.

3. Intercellular bridges.

H. and.

_——_~*—_——.“‘—*“A_—m——a—

 

62

 

PLATE XI

Section from subcutis of foot pad showing a large Pacinian
corpuscle, large nerve trunk, blood vessels and special
nerve ending resembling those in Plate X. H. and E.
260x.

1. Pacinian corpuscle.
Nerve trunk.

Large blood vessel.

kWh)

Adipose tissue.

Special nerve structure.

\Tl

 

O\
U‘l

PLATE XII

A longitudinal section through the supracaudal gland

area in the proximal dorsal portion of the tail.

H. and E. 13X.
1. Large
2. Large
3. Large

4. Large

well developed arrector pili muscle.
sebaceous glands.
saccular sweat gland.

hairs.

(‘N

L‘W

 

66

 

67

'PLATE x111

Section of guard hairs showing the follicular folds.

Wright's blood stain modified for tissue, 465X

1.

2
3
4.
5
6

Undulations of the stratum corneum showing
follicular folds.

Granular layer.

Stratum spinosum.

Sebaceous gland.

Excretory duct of sweat gland.

Mast cells.

 

 

69

PLATE XIV

Oblique section through the lip. H. and E. 13X.

1.

2
3
4.
5

0\

Large sebaceous glands.
Blood filled sinus.
Large tactile hair in the center of blood sinus.
Large sweat glands.)

Note that the entire stratum reticulare portion
of the lip is taken up by the large glands.
Smaller hair follicle.

Orbicularis muscles.

 

 

 

70

 

71

PLATE XV

Longitudinal section from the hairy skin showing
branching arrector pili muscle. Wright's blood
stain, 464X.

l. Epidermis.

2. Arrector pili muscle.

3. Mast cells.

 

 

72

 

PLATE XVI

‘Longitudinal section through the lip, showing large

sebaceous glands, coiled sweat glands. H. and E. 12X.

1.

2.

\n

Large sebaceous glands.

Small sebaceous glands.

Coiled sweat glands shown entering hair

follicles.

Blood vessel.
Small nerve trunk.

Striated muscle fibers of tactile hairs not

shown in this section.

 

'11 ‘llllllll'llil'irillil

.C

74

 

\H

M

PLATE XVII

Lon itudinal section through the upper eyelid showing

(

interior border of the lid, linear series of tarsal

glands,

and saccular type sweat glands. H. and E. 8X.
Saccular apocrine sweat glands.
Tarsal glands.
Ring of sebaceous glands (upper portion of
hair follicle).
Roots of hairs.
Large hairs of eyelids.
Coiled apocrine sweat glands.

Collagenous and elastic fibers.

 

 

76

77

PLATE XVIII

Sweat glands of the scrotum. H. and E. 248X.

1.

2.

Large secretory unit of the sweat gland.

Excretory portion of the gland.
Hair follicle.

Loose connective tissue fibers.

 

 

 

 

——. —_—._ _.——

-——.———'-.—

19‘ . \~‘
1) -‘ l '5
.3: TL 1 ' . . ’
T'K" : x A ' h
ixf.‘ ‘1 o '4
.3 a ‘
-. -’-. ~ 1 "
u"

 

78

79

PLATE XIX

Frontal oblique section of tactile hairs showing

small sebaceous glands at proximal portion, also

showing different hair levels. H. and E. 13X.

1.

Small sebaceous gland inside of connective
tissue annular ring.

Increasing thickness of connective tissue
near the proximal portion of hair as com-
pared to other levels.

More distal hairs associated with large
sebaceous glands. I

Saccular sweat gland.

Epidermis with papillae like structures.

Sebaceous gland in a secretory condition.

 

 

a... 1"",1. I

{I’IlL'ER ..

. 3|»

 

80

 

81

PLATE XX

Longitudinal section in the hairy skin area showing
small saccular sweat gland emptying into the upper
portion of the hair follicle. H. and E. 360x.
1. Excretory duct of the saccular sweat gland.
2. Arrector pili muscle at the base of sweat
gland.

3. Three hairs converging toward a common opening.

 

.II t.’ 11'

 

83

PLATE XXI

The anal sac and associated glands. Note the large

coiled sweat glands, and the large cluster of sebaceous

glands secreting into the anal sac lumen. H. and E. 11X.

1.

2.

H?

O\\)')

Coiled sweat glands.

Cluster of sebaceous glands.

Stratified squamous epithelial lining of the
anal sac.

Skeletal muscle.

Connective tissue.

Saccular apocrine sweat glands.

 

a .
'K \ x; 4 'f%\ ““%5"-\ ‘ \‘\\\‘¢§%
. r." ‘ § ‘ g’ 3 “ ‘ ‘ , ‘ 3. A“.
‘. . r ‘ - 1 4‘: s-.. ‘ ‘\
a ‘ I .4“ I '

 

\I)

PLATE XXII

Sections of the teat. H. and E. 43X.

.1.

2
3
u.
5

Sebaceous gland.
Milk ducts.
Epidermis.

Stratum papillare.

Stratum reticulare.

 

86

 

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87

88

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Additiona145eferences Not Cited

 

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