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Michigan State
University

 

THE ANAL SACS OF THE DOMESTIC CAT, F9118 domesticus

 

By

3,.
Marjorie Greer

A THESIS

Submitted to
The College of Veterinary Medicine
Michigan State University
in partial fulfillment of the requirements
for the degree of

MASTER OF SCIENCE

Department of Anatomy

1961;

60'.\VU'

9/1/34

ACKNOWIEGMENI‘S

I wish to'aclmowledge the kind supervision and guidance of-
fered by Dr. H. Lois Calhoun, Professor and Head of the Department
of Anatomy, College of Veterinary Medicine, Michigan State Univer-
sity. Appreciation is also due the entire faculty of the Department
of Anatomy for their assistance and encouragement throughout the
preparation of this thesis. I an grateful for the assistance in
the preparation of the photomicn'ographs provided by Dr. Esther M.
Smith and Mrs. Jan Sharon. Special. thanks also are due Dr. Esther
Roege for her helpful suggestions regarding microtechniques, and
for her enthusiastic interest in the project.

Thanks are extended to the friends who provided specimens for
the study and to my fellow graduate students for their faithful en-
couragemerrt.

I achiowledge the financial assistance of a training grant pro-
vided by the Vocational Rehabilitation Administration, Department of
Health, Education and Welfare and administered by the American
Physical Therapy Association.

Finally, I particularly want to thank my husband, J. Keever
Greer, for his untiring assistance and encowagement.

TABLE OF CONTENTS

INTRODUCTION. . . . . . . . . .
LITERATURE REVIEW
General Summary of the Literature. .
Gross Anatomy. . . . . . . .
Microscopic Anatomy and Histochemistry.
Function. . . . . . . . . . .
MATERIALS AND METHODS
Gross Anatomy. . . . . . . . .
Microscopic Anatomy and Histochemistry.
RESULTS AND DISCUSSION
Terminology. . . . . . . . . .
Gross Aspects. . . . . . . . .
Microscopic Aspects. . . . . . .
General Appearance. . . . . . .
Anal See and Duct. . . . . . .
Sebaceous Gland Complexes. . . .
Apocrine Glands. . . . . . . .
Histochemistry. . . . . . . . .
SUMMARY AND CONCLUSIONS. . . . . . .

LITERATURECITED. . . . . . . . .

~111-

Page

O\\n\»l\)

13
13
18
18
18
20
23
28
30
33

Table

1.

2.

3.

IJST CF TABIES

Page

Body lengths, hind foot lengths and dimensions
of gross aspects of anal sacs of embalmed cats. . . . 16

Body lengths, hind foot lengths and dimensions
of gross aspects of anal sacs of fresh cats. . . . . 17

Body lengths and dimensions of microscopic parts
of anal sacs of cats. . . . . . . . . . . . 27

Plate
I.
II.

III.

IV.
V.

VI.

VII.

VIII.

XII.

XIII.

LIST OF PLATES

Anal sacs exposed by dissection. . . . . .
Ana]. 880 With duet. e e e e e e e e e

Pacinian corpuscle in connective
tissue of sec wall. . . . . . . . . .

Reticular tissue surrounding sebaceous alveoli.
Sebaceous gland complex. . . . . . . .

Portion of sebaceous gland complex showing
cellular disintegration. . . . . . . .

Portion of sebaceous gland complex showing
fat distribution. 0 e e e e e e e e

Portion of sebaceous gland complex showing
glycogen distribution. . . . . . . . .

Apocrine duct opening into sac lumen near
sebaceous gland complex. . . . . . . .

Apocrine gland duct opening into sac lumen. .

Apocrine gland tubules. . . . . . . . .

Apocrine gland tubules. . . . . . . . .

Reticular tissue surrounding apocrine tubules.

.v-

Page
35
36

37
38
39

to

1:2

143

145

146
Lt?

THE ANAL SACS OF THE DOMESTIC CAT, Felis domesticul

INTRODUCTION

Anal sacs (Ling measles) are small, paired organs, the
walls of which contain glands. These sacs are located lateral to
the anal canal and connect to it by means of short ducts. The
presence of these sacs is characteristic of many species of the
Order Carnivore (Class Mamalia).

Investigation of these small organs seemed justified because
little regarding the anal sacs of cats has been published since an
article by Otto Ironing appeared in 1926. The study for the fol-
lowing report was undertaken in order to gain a better understanding
of the gross and microscopic anatomy of the sacs and of some of the
chemical properties as revealed by simple histochemical techniques.
Some of the data presented here are in extension, clarification and
corroboration of the fine work published by Dr. Krolling.

LITERATURE REVIBVI

General Sumary of the Literature

In 1926, an article written by Otto KroILling (1926) about
the anal sacs of the domestic cat appeared in a German anatomy
journal. In this article, the microscopic anatomy of the anal
sacs of the adult animal and of the sacs of embryos of differ-
ent ages was described. Remarks related to the function of the
organ and speculations regarding phylogeny also were made. An-
other review of the subject appeared in Schaffer's work (19h0)
on the skin glands of manuals, with special emphasis on the glands
of the anal region of the dog, including those of the anal sacs.

Description of anal sacs in text books of anatonw of the do-
mestic animals have been brief (Ellenberger, 1911; Ellenberger
and Baum, 1916; Martin, 1923; Keishard and Jennings, 19130; Trautnann
and Fiebiger, 1952). Mention of the anal use of cats, dogs, and
weasels was included in an English summary of a Japanese article
(Katsuna, 1959) about the comparative histology of glands of the
perineum of female manuals.

Descriptions of the anal sacs of other carnivores, especially
dogs, have been published. Titkemeyer (1958) clarified some of the
confusing terminology used in relation to the glands and other
structures of the perineal region of the dog. Diseases and treatment
of anal sacs of dogs were discussed by Baker (1962). An extensive

-3-

histochemical study of the anal sacs of dogs was made by Mantegna
an! Parks (l9h8). Discussions of anal sacs appear in reports of
studies on other animals, such as the mink (Kainer, 1994), tiger
(Hashimto, gt 51:, 1963) and the skunk, (Mephitis mefltis)
(Cuyler, 1921; and Schwartz and Schwartz, 1959).

Function of glands, similar to anal sac glands, found in the
armadillo (132m novemcinctus , Order Edentata) was investigated
by Haynes and Enders (1961), and functional aspects of glands, in-
cluding anal sac glands, which produce odorous substances in mammals
were discussed by Parkes (1960). Cuyler (1921;) and Schwartz and
Schwartz (1959) discussed the functional aspects of the anal sacs
of skunks.

Gross Anatony

The gross anatonw of the anal. sacs of various members of the
Order Carnivore has been discussed by various authors, but usually
briefly. According to Reighard and Jennings (191m), the anal sacs
of the cat are approximately one centimeter in diameter and open
into the anus at a point one or two millimeters from the caudal
boundary of the anus.

The anal sacs of dogs are reported to be lateral and slightly
ventral to the anus between the M. sflincter g externus and M.
sphincter 52.1 internus (Martin, 1923 and Titkemeyer, 1958).
Ellenberger and Balm (191.3) stated that the anal sacs are the size
of peas in young dogs, and as large as walnuts in adults. They

further stated that the duct of each sac opens into the Zone cutanea

.1...

by way of an orifice the size of a pinhead. Montagna and Parks
(l9h8) reported that the anal sacs of the dog are the size of a
pee or hazel nut, are located between the internal and external
anal sphincter muscles, and open “ventrally on the lateral margin
of. the anus“. Baker (1962) reported the sizes of the anal sacs
in the dog to be between seven and twenty millimeters and said the
sac ducts open at the ano-rectal Junction. Schaffer (19,40) de-
scribed the anal sacs as egg-shaped and reported that they measure
nine by seven millimeters.

Hashimto, 9.1.". g. (1963) found the anal sacs of the tiger po-
sitioned similarly to those of the dog and cat and that they are
three by two and one-half centimeters in size. He reported each
sac duct opens into a nipple located in the cutaneous zone adjacent
to the ans-cutaneous line. Cuyler (1921;) and Schwartz and Schwartz
(1959) wrote that the orifices of the anal sac ducts of the skunk
(Family Mustelidae) also are located on nipples in the anal wall.
and that the nipples are projected to the outside when the tail is
raised in readiness for discharge of the musk. Cuyler (1921;) noted
that the skunk sacs are egg-shaped.

Rainer (1951;) described the sacs of the mink, another mustelid,
on each side of the cutaneous zone of the anus, and connected by
mm of a short duct to an opening near the sac-cutaneous line. He
wrote that part of each sac is located between the internal and ex-
ternal anal sphincters, that the external sphincter is thin at the
dorso-laterel surface of the sac, and the fundus of the sac extends

beyond the anterior border of the thin part of this muscle into the

-s-

fat-filled ischio-rectal fossa. He reported a lobulated, gland-
like structure surrounding the neck of each sac.

According to Titkemeyer (1958) the anal sac of the dog re-
ceives its blood supply from the caudal hemorrhoidal artery and
is innervated by the internal pudendal nerve.

Microscopic Anatomy and Histochemistry

The most comprehensive discussion of the microscopic anatonw
of the anal sacs of the cat was presented by [rolling (1926).
This work will be referred to later, in the discussion of the mi-
croscopic aspects of these orgam. Hontagna and Parks (1926)
in their report on the histo-chemical aspects “of the anal sacs of
dogs, stated that these organs are situated between the external
and internal anal sphincter muscles. The sees and ducts were said
to be lined with keratinized, stratified squamous epithelium, sur-
rounded by glands embedded in a connective tissue stroma rich in
diffuse lymphatic tissue with occasional lymph nodules. They re-
ported apocrine , sudoriparous tubules with myoepithelial cells and
basement memllranes, surrounding the fundus of the sac and opening
into it, and large sebaceous acini in the walls of the sac ducts.
They also reported that the apocrine glands secrete serous fluid
and the sebaceous glands secrete most of the lipid portion of the
anal sac products.

Ellenberger (19ll) stated that the wall of the anal sac of
the dog contains a type of sweat gland which produces a fatty se-
cretion, and that the wall of the sac duct contains sebaceous

-6-

glands. In cats, he described branched alveolar sebaceous glands,
as well as branched tubular sweat glands, in the sac wall. He fur-
ther reported lymph nodules in the lamina propria of the anal sacs,
and peculiar cells "not dissimilar to neuro-epithelial cells" in the
epithelium of the sac wall. Contrary to other accounts, Trautmann
and Fiebiger (1952) believed there are both tubular and alveolar
glands in the excretory ducts of both dog and. cat. The presence of
leucocytes in the apocrine tubules in the dog was noted by Schaffer
(19110) and in the cat by Krolling (1926).

Bashinoto, 93 31. (1963) found that the anal sacs of a tiger
also possess a keratinized lining of stratified squamous epithelium
and a thick muscular band of irregularly arranged skeletal muscle
bundles. They found the connective tissue stroma contains many high-
ly convoluted, branched tubules connected to a collecting duct open-
ing into the sac lumen, and that the tubules possess myoepithelial
cells and basement membranes. The presence of a few alveolar glands
composed of polygonal cells which stained strongly with Sudan IV
also was reported. 7 7 I

Tagawa (cited by Hashinoto, at 31., 1963) reported that the
anal sacs of the skunk have only apocrine glands which are arranged

mainly around the equatorial zone of the sac.

Function

Various statements have been made regarding the function of
anal sacs. Krolling (1926) reported that the activity of the

glands is related directly to the breeding condition of the animal.

-7-

According to his results, the apocrine and sebaceous glands reach
their maximun.activity during mating seasons, and that the seba-V
ceous glands are inactive at times other than.the mating seasons.
He found no difference in secretion intensity'between.the sexes.
He concluded that the function of the sac glands is to provide a
secretion, which by virtue of its odor, would help to bring the
male and female together during the mating seasons. Schaffer (19h0)
concluded a similar function and added that at times other than the
heat period, the odor of the sac secretion served for identification.
Gerstenberger (cited by Krolling, 1926) reported a correlation
between anal sac secretion of the dog and the reproductive cycle,
as did Schaffer (191:0). Baker (1962) believed the biological sig-
nificance of the dog anal sacs is unknown, but listed three theories
related to their function. In addition, he reported that the dog
may discharge anal sac fluid when frightened. He discredited the
theory that the secretion provides a lubricant to aid defecation, on
the basis of the distal location of the sacs. The other theories
cited were that the secretion provides a characteristic smell, and
that it might be used for territory marking. Parkes (1960) supported
these last two theories by asserting that they apply to odorous se-
cretions in general from glands of mammals. He further stated that
such secretions provide an identifying odor to attract the male to
the estrous female. George A. Petrides (personal communication)
stated that tom.cats, captured in traps set for wild fur-bearing
animals, released a marked odor, subsequent to handling, which he

believed to originate from anal sac secretions.

-8-

Hashimto, _e_t_ g. (1963) believed the biological and physio-
logical significance of the anal sacs of the dog and cat is obscure.
Montague and Parks (19h8) in their report on the histochemistry of
the anal sacs of the dog, advanced no theories or conclusions re-
garding function.

Haynes and Enders (1961) reported glandular structures of the
armadillo, 2222225 novemcinctus, to be active all year. The de-
scription of these organs was similar to that of anal sacs. They
suggested that the secretion might serve in marking trails or as a
defense mechanism. The only relation to the reproductive cycle
found was an increase in.glycogen in the apocrine glands of the sac
during induced ovulation.

Schwartz and Schwartz (1959) reported that a "strong odor“
is given off by the musk, or anal sac, glands of the mink, espe-
cially during the breeding season, but also during any period of
intense excitement. They'reported that musking by the skunk occurs
mostly in self-defense and that only rarely is the anal sac secre-
tion released when skunks play, engage in fights with other animals,

or when the females are in heat.

MATERIAIS AND METHODS

Gross Anatonw

Of a total of 57 cats used in this study, 17 adult female and
11; adult male embalmed house cats were chosen for gross dissection
and measurements. Dissection and measurements were also performed
on 1; adult female, 1 imature male and 2 adult male cats before
fixation. The following measurements were made: internal lengths
of the sac lumens of embalned specimens, dimensions of the sacs of
the unembalmed specimens, both includingand excluding the external
anal sphincter muscle covering the sacs, and dimensions of the se-
baceous gland complexes. A caliper was used to make the measurements.
The measurements were correlated with sex and size differences. The
arterial supply to the sacs was noted in embalmed specimens which
had been injected with colored latex. General gross observations were
made on all animals dissected.

Microscopic Anatonw and Histcchemistry

Anal sacs of 5 adult cats (2 males an! 3 females) and 10 in-
mature, unembalmed cats (8 males and 2 females) were selected to
be fired, embedded in paraffin blocks, sectioned and stained. In
addition, I; embalmed cats (1 male and 3 females) were handled 81l-
ilarly. Some cellular and tissue distortion was present in the sec-
tions made of the sacs taken from the embalmed cats; nevertheless,

-9.

-10-

they were useful in investigation of general structural charac-
teristics.

With the exception of one see which'was fixed in.lO% alcohole
formalin for preservation of glycogen, all the anal sac specimens
'were fixed in 10% formalin. The specimens were stored in.70% I19
cohol until further processing.

Most of the specimens were dehydrated and cleared in four
changes of dioxane. Three specimens were dehydrated in.a graded
series of alcohol and cleared in cedar oil and xylene in an.unr
successful attempt to obtain a tissue specimen which could be more
easily sectioned. The specimens were infiltrated with.paraffin in
a vacuum oven prior to embedding in.paraffin. During infiltration,
the oven mechanism was operated so that 15 minute periods of atmos-
pheric pressure alternated with 15 minute periods of partial vacuum.
One specimen was double-embedded in celloidion and paraffin. sec-
tions were cut at 6-? microns on a rotary microtome.

IThe tissue sections tended to fragment when floated in a water
bath, so were placed directly on a glass slide to avoid fragmenta-
tion. A few drops of water, in which a small amount of gelatin had
been dissolved, were placed on.the slide to aid in flattening the
section, and the slide was drained and dried. The slides were coated
with albumin adhesive until it was ascertained that this precaution
was unnecessary. The sections were subsequently stained and mounted.
One formalin-fixed specimen was sectioned on a sliding, freezing mi-
crotome prior to staining for evidence of lipids.

The tissues were found to be especially difficult to prepare

for sectioning and several variations in schedules of the dehydration

.11-

and embedding procedures were employed. No completely satisfactory
method was devised since the reasons for the difficulties were not
found.

Several different stains were used to investigate various as-
pects of the chemical and structural nature of the anal sacs. Gen-
eral tissue staining was achieved with a.modified Harris' hematoxylin-
eosin stain (Malawitz and Smith, 1955). Grossmon's modification of
Mallory‘s triple stain (Crossmon, 1937) was used as a general stain
and to differentiate collagenous connective tissue. Reticular cone
nective tissue was demonstrated, using a Lillie modification of
Gomori's silver technique (Lillie, l95h) and by a modification based
on a combination of techniques of Gridley'(1957) and Lillie.

The presence of acid mucopolysaccharides was tested by’Gridley‘s
(1957) Alcian blue method. P.A.S. techniques of Lillie (19514) and
Gridley were used to test for the presence of carbohydrates with
1,2 glycol groups; a combination.Alcian blue-P.A.S. technique of
McManus and Mowry (1960) also was used. Gridley‘s Oil.Red 0 pro-
cedure was used on frozen sections to determine the presence of 119
pids.

Various structures were measured with an ocular micrometer.
Measurements and means were recorded (Table 3). Due to irregularis
ties in the shapes of the structural components of the anal sacs,
measurements which could be considered representative were limited.
In addition, special care was taken in selection of the various

measurements and in interpreting these measurements. Because of

-12...

the irregular shapes of the structures in the sac, and the aber-
rations which naturally result from sectioning tissue, some of
the figures presented may be regarded as approximations. Large
variations (Table 3) made statistical analyses impractical.

RESULTS AND DISCUSSION

Terminology

The anus usually is considered to be divisable into three
zones, viz.: the Eggs; columnaris, the 2.9.92 intermedius and the
£393 cutanea. The anus is lined by stratified squamous epithelium.
The Egg columnaris is the most cranial portion and joins the rec-

tal mucosa at the Lines ano-rectalis. It is characterized by long-

 

itudinal folds, the Columae _a_n_i, and is found only in man, dog,
cat and swine (Ellenberger and Baum, 1910). The 5: intermedia is
hairless and glandless and joins the 5:. cutanea at the £1303 E
cutanea. The _z_.. cutanea is the distal link to the outer skin of
the perineum and has dermal papillae, hairs and associated seba-
ceous and sweat glandsand, in the dog and cat,circumanal glands
(Ellenberger and Baum). The above classification was made by
Mladenowitsch (cited by Ellenberger and Emma) and both the Latin

and Anglicized versions of the terms are used in the following re-

port.

Gross Aspects

The two anal sacs of the cat were situated laterally and
somewhat ventrally on opposite sides of the anus (Plate 1). Their
caudal walls were approximately one centimeter from the perianal

skin. The short ducts opened at the level of the aha-cutaneous

.13-

.33..

line (designated as that line cranial to which hair was not dis-
cernable). The ducts, at their openings into the anus, appeared

as small, wrinkled tubules. Thin layers of the external anal
sphincter muscle, which also encircled the anus, covered the sacs
and appeared as a comnon sheath surrounding both sacs and the por-
tion of the anus between the sacs. The sacs, with their muscular
covering, were embedded in a pad of fat. 0n removal of the muscle,
a capsule of connective tissue was seen in which were embedded four
to nine yellow, spherical bodies (an average of 5.8 on the basis of
six observations). These yellow bodies were later found to be ac-
baceous gland complexes (so designated to distinguish them from the
sebaceous glands typically associated with skin), which measured up
to 3 to h m. at their longest axes (Table 2). The linings of the
sacs of fresh specimens were smooth and white. The lumens of the
sacs of the embalmed cats were kidney-shaped or bean-shaped, but the
shapes of the lumens of the fresh specimens could not be observed
due to their tendency to collapse when opened.

Each sebaceous gland complex Opened by a single duct into the
lumen of the anal sac; the tiny openings of these small ducts were
visible grossly on examination of the interior of the sac. Various
amounts of yellowish or grayish-white liquid, slightly more viscid
than water, usually could be expressed from the unembalmed specimens.
This secretion had a characteristic, pungent, "cat-like" odor.

Dissection of embalmed specimens showed the anal sacs to be
supplied by branches of the middle hemorrhoidal artery, the princi-

pal vessels passing over the muscular covering at the ventro-nedial

-15..

aspect of each sac. The middle hemorrhoidal nerve, a branch of the
pudendal, was reported by Reighard and Jennings (191.10) to innervate
the muscles and other structures about the caudal and of the gastro-
intestinal tract, so was assumed to innervate the anal sacs also.
The innervation might be bilateral since the external anal sphincter
muscle receives bilateral innervation from the pudendal nerves
(Bishop, 1959). However, identification of the nerve supply was

not made in the present study.

The measurements made on adult, embalmed cats are recorded and
summarized in Table 1. In order to relate the size of the sac lu-
men to the size of the animal, the length of the sac per millimeter
of body length and per millimeter of hind foot length was determined.
Body length was measured from the base of the tail to the tip of the
nose, and the hind foot was measured from the end of the calcaneous
bone to the tip of the longest toe.

The’average size of the female sac lumens was greater than in
the male. Moreover, the sizes of the anal sac ltmens of the females
as related to body length and to hind foot length were, on an aver-
age, larger than those of the males (Table l). The differences be-
tween the males and females in the sac-body length ratios and the
sac-hind foot length ratios were found to be significant using a
two-tailed test at the 5 per cent level.

Measurements made of unembalmed cats are recorded and sumar-
lead in Table 2. Statistical analyses were not attempted because
of the small size of the sample, but comparison does not show a
marked or surprising deviation from the figures for the embalmed

specimens (Table l).

-16-

Table 1. Body lengths, hind foot lengths and dimensions of
gross aspects of anal sacs of embalmed cats

 

 

"7 '8 .3
a -= E a a
g g» o 3 o h
f5 H H I: a " 4‘3
g +3 g +2 a. 3‘3 g
a .3 5 8" a ifs
a. H "' 3? H *3
'8 3 s a? a 8.3
m :11 U) U) 01
h80* 106 10.1 .0210 .0953
h68 10h 10.h .0222 .1000
h57 111 9.5 .0208 .0856
8 h55 110 1 .1 .0222 .0918
'g nus 10h 7.5 .0169 .0721
“' h30 10h 8.5 .0198 .0817
932 _92 1 .2 .0238 .1030
Range 1129-1480 99-109 7 .1-10. h e 0160' e 0238 e 0651- e1030
Mean h51 106 9.18 .0203 .0868
s.d.** 1.3 .0027 .0133
526 115 8.2 .0156 .0713
525 123 10.1 .0192 .0821
510 116 10.6 .0208 .09lh
505 120 10.5 .0208 .0875
502 113 6.7 .013h .0593
h75 115 6.h .0135 .0557
a h75 119 7.8 016h .0656
m h7h 115 6.6 .0139 .057h
g 1.73 113 6.7 .01h2 .0593
h63 113 l .1 .0218 .089h
h59 107 7.0 .0153 .065h
h55 108 9.7 .0213 .0898
Egg, 192 .ZLZ .0173 .0706
Range hh6-526 109-123 6.6-10.6 .013u-.0218 .0557-.09lh
Mean hBh 11h 8.32 .0172 .0727
S.d.** 1.3 .0032 .0136

 

* All measurements in millimeters
#8!- Standard deviation

-17-

Table 2. Body lengths, hind foot lengths and dimensions of
gross aspects of anal sacs of fresh cats

 

 

.g) +3 3 H
a '3 8 8 ti 3
g. a :3 3 a a
e .5 '5 ‘8 a 8
.s ri n r4
.9 .2 .s m g
3’ *3 *’ *’ ‘8‘ fl ‘8 o
(D O 2'? 0 g 0 Q) 0
"' ‘H .3 a .3 '23 a '3. g 3
>5 (0 m E ,0
a E as 82 38 .2
a1 a: ca 01 :z .4
Mture 11.2 11* 117 ll . 3 --- --- ---
females h32** 11h 10.1 --- --- --
12.3 --- --- ---
h77 121 8.0 6.7 5 3.3
1181“ 121 10.5 7.3 5 3.8
__ __ _n-1 2.9 1... .11
Mean (4511 118 10.5 707 he? 3e
"final; ’ 381a; " ' -83 — " " -8:h_ — " “-1- - ' "-11- " — '3: -
male 1:1 --- --- --
Mean e1
"Mall; ' " E36 " " "' 1'23 " " " 10:5” ’ _ "-3-— ” ' "'9 ''''' u ".0" "
males --" 117*” 808 5e8 6 3e2
__ _9.5 6.1 9. __
Mean 120 9. 6.0 7 3.

 

-* All measurements in millimeters
** Measurements of both anal sacs of this specimen included

-13..

Microscopic Aspects

General Appearance. Microscopic sections of anal sacs of cats
cut on a plane transverse to the anus (Plate 11) showed the walls to
be composed of white fibrous connective tissue in which were embedded
two types of glands, viz.: alveolar sebaceous glands clustered to-

gether in large, ovoid complexes, and coiled, tubular apocrine glands

 

structurally similar to other apocrine glands of mammalian skin. The
glands were arranged densely in the sac wall with apocrine glands in-
terspersed between sebaceous complexes. The sacs were lined with
keratinized, modified stratified squamous epithelium. The walls of
the sac excretory ducts also comisted of white fibrous connective
tissue, and were lined with keratinized, stratified squamous epithe-
lium. The duct epithelium was continuous with that of the sacs, but
consisted of more layers and was more highly keratinized than the
epithelium of the sac. The ducts connected the sacs to the anus and

opened at the Linea ano-cutanea. A band of skeletal muscle fasci-

 

culi (y_._ sphincter .92. externus) was found between the exteer
sphincter muscle surrounding the sac, and the anus, but extended

 

 

only to the level of the aha-cutaneous line, and did not appear re-
lated to the anal sacs or ducts.

Anal Sac and D113}. The anal sac was lined by keratinized, mod-
ified stratified squamous epithelium which did not form rete pegs
(Plates IX and X). The basal layer of epithelial cells consisted
of regularly arranged, columnar or cuboidal cells resting on a flat

basement manbrane. The nuclei of the basal layer contained dense

-19-

chromatin, art! were situated at approximately the same level, 1.9.,
at the same distance from the basement membrane. These basal cells
usually were overlaid with one, but sometimes two, layers of irregus
larly arranged polygonal cells, with a final layer of squamous cells,
although often only the basal layer of columnar cells was evident.
The intermediately placed cells were larger and had nuclei with less
dense chromatin than the basal cells. An area of keratinization se-
parated these epithelial cells from the sac lumen. The epithelial
height varied considerably, but averaged about 11 microns high at
the lowest points. (The true, overall average was not determined.due
to the probability for error caused by tangential sectioning.) The
epithelial lining rested on a bed of connective tissue which was com-
posed mainly of collagenous tissue containing blood vessels, nerves,
and, in one specimen, two small Pacinian corpuscles were observed
(Plate III). Often, the area of connective tissue was infiltrated
with leucocytes. Very little elastic tissue-o-less than.that ob-
served in'the dermis of the anus--was demonstrated. Argyrophilic
reticular tissue was present, mostly concentrated directly under the
epithelium in the form of fibers running parallel to the basement
membrane (Plate IV).

The anal sac duct (Plate II) was lined by stratified epithelium
similar to that Observed in the sac lining, but had more cell layers
between the basal layer and the lumen, and had a thicker area of
keratinization. The epithelium was usually two to four layers in
thickness. (At the areas where the epithelium.was lowest, the aver-

age height was about 19 microns.) By observing a series of cross

-20-

sections of the anus it was determined that each anal sac duct opened
at the aha-cutaneous line, so that the caudal part of the orifice was
continuous with the cutaneous zone, and the cranial part with the in-
termediate zone. Plate II is a photograph of a section cut at an area
where the duct opens into the intermediate zone. The duct lumens,
measured at the widest points, averaged about 1 mm. in diameter and
the lengths, measured between the anus and the anal sac, averaged
about h an. (Table 3). The connective tissue surrounding the duct,
similar to that around the sac, was mainly collagenous with armo-
philic reticular fibers concentrated under the epithelium. The elas-
tic fibers were more abundant than in the sac wall and appeared to ‘
be of the same concentration as that seen in the dermis of the anus.

Small fasciculi composed of thin skeletal muscle fibers surrounded
the anal sac (Plates II andv). As noted grossly, this band of mus-
cle also encircled the anus. As seen microscopically, parts of this
muscle layer extended into the area between the sacs and the anus.
Smooth muscle of the internal anal sphincter muscle was observed be-
tween the skeletal muscle and the anus cranial to the level of the
duct opening (i.e., at the aha-cutaneous line), but did not appear
related to the sacs or ducts. Skeletal muscle also was arranged cir-
cularly around the sacduct, external to the connective tissue sheath
of the duct (Plate II). The skeletal muscle was supplied with num-
erous nerves and blood vessels.

Sebaceous Gland Complexes. The sebaceous gland complexes, the
gross appearance of which was described earlier, were seen to be dis-
persed in the connective tissue of the wall of the anal sac at fair-
ly regular intervals. Cross sections of the anal sacs showed two

or three sebaceous gland complexes in each cross section, giving a
general idea of the distribution of the complexes in the sac wall.

The connective tissue surrounding a complex was similar to,
and continuous with, that surrounding the epithelial lining of the
anal sac and that in which the apocrine glands were embedded. The
thickness of the connective tissue layer between the sebaceous com-
plexes and the surrounding skeletal muscle varied between 12 and 17h
microns (Table 3). This was considered as an outer capsule enclosing
the anal sac and the anal sac glands. The connective tissue surrounds
ing the sebaceous complex was continuous with the sparse stress a-
round the individual alveoli of the sebaceous complex itself. Often
lymphocyte infiltrationnwas noted both in the stroma of the glandus
lar complex, as well as in other parts of the anal sac wall. Sever-
al of the sebaceous complexes appeared to be composed of indistinct
lobules of sebaceous gland units; the lobules were separated from
each other by small amounts of collagenous and reticular connective
tissue. Blood vessels and occasional apocrine ducts were embedded
in the connective tissue (Plate II).

The typica1.individual sebaceous gland unit, or alveolus, was
similar to sebaceous glands associated with hair follicles of the
skin in that it was composed of central polygonal or spherical, van
cuolated, sebaceous cells enclosed by smaller, flatter cells forming
a capsule-like arrangement around the central cells (Plates VI and
11). However, the sebaceous cells of the alveoli of the anal sac
glands were generally smaller and usually stained more darkly than

those of the sebaceous glands of the dermis of the cutaneous zone of

-22..

the anus. Measurements of the lengths of the sebaceous alveoli
averaged about 85 microns (Table 3). Each individual alveolus was
surrounded by'a thin, and sometimes indistinct, framework of collar
genous and reticular connective tissue (Plate IV).

Krolling (1926) stated that the sebaceous excretory ducts were
tubules consisting of one to two layers of epithelium. The present
investigation indicated that the beginning of an excretory duct was
formed by degeneration of sebaceous cells located in the center of
an alveolus (Plate VI). The lumens formed by these areas of disinp
tegration led into epithelial-lined ducts similar to those described
by Krolling. The ducts, scattered throughout the sebaceous gland
complex, converged and joined to form larger ducts. The final union
of the ducts formed a large cistern.which emptied into the lumen of
(the anal sac (Plate IV). The ducts were supported by‘a stroma of
collagenous and reticular connective tissue. Measurements of the luv
men diameters of the largest ducts, excluding the cisterns, of the
sebaceous complexes varied between 23 and 160 microns with an average
of 2-3 cell layers composing the epithelial linings.

The mouths of the cisterns, as noted earlier, were visible
grossly as they opened into the sac lumen. The cistern lumens at
’ the widest diameters varied between 117 and 560 microns (Table 3).
The epithelial linings of the ducts, cistern and anal sac were cons
tinuous. .At the beginnings of the sebaceous gland duct systems, the
lining cells were greatly flattened, only one layer thick, and not
keratinized. Progressing toward the cistern, the lining cells be-
came more cuboidal and the layers more numerous, and abundant kera-

tinization was visible. Where the diameters of the cisterns were

-23-

widest, the average height of the epithelium was about 20 microns
with three cell layers.

Apocrine Glands. The apocrine glanis were embedded in the con-

 

nective tissue of the anal sac wall (Plates II and III) between and
surroundirg the sebaceous complexes, except at the outer-most limits
of the sac wall. Krolling (1926) stated that there were up to 30
apocrine glands present in one anal sac. In the present study at-
tempts to count the apocrine glands were not undertaken, because it
seemed impossible to«distinguish one gland from the adjacent glands
by examination of microscopic cross sections. The connective tissue
in which the glands were embedded was similar to other connective
tissue stroma described earlier. It was composed mainly of colla-
genous tissue with little elastic tissue, contained blood vessels and
nerves, and frequently was infiltrated by diffuse lymphatic tissue,
and occasionally organized nodules. There was considerable argyro-
philic, reticular tissue present around the tubules (more than that
observed around the sebaceous alveoli), so that the silver stain
clearly outlined these glands (Plate XIII). The tubules of the glands
appeared tortuous and coiled as evidenced by the large numbers of
cross sections or tubules seen in.one area (Plate II). The most exp
tensive glands, measured from.the sac lumen to the distal limit of
the gland, were about 2 mm. in depth (Table 3). The outer, or distal,
limit corresponded approximately with.the outer limits of the sebap
ceous complexes. In places, the tubules appeared to branch, or formed
diverticuli similar to the apocrine glands of human skin.described by

Montague (1962). The tubules were lined by simple columnar or cuboidal

-2h-

epithelial cells which varied in height and structure. Many of the
luminal borders of the cells appeared to form cytoplasmic extensions
into the lumens, whereas some were smooth (Plates XII and XI). The
tubules were surrounded by a thick-appeang basement membrane and
myoepithelial cells were discernible between the basement membrane
and the epithelial cells (Plate XI). Based on the shapes of the
nuclei, these myoepithelial cells appeared to be arranged in the
manner described by Goldstein (1961) for myoepithelial cells of apo-
crine glands of the human ear, i.e., as elongated cells with their
long axes parallel to the long axis of the tubule. Tubules of all
specimns examined contained leucocytes in various concentrations
and many tubules contained small globules of unidentified material
(Plate II).

Diameters of the lumens of the apocrine glands and heights of
epithelial cells varied widely (Plates II and III and Table 3).
Measurements of the largest lumens ranged up to 1:88 microns and
averaged about 100 microns (Table 3). Lumens, other than the largest
ones just mentioned, and which appeared to be fairly representative
of a random selection, ranged from h microns to 30 microns and had
an average diameter of about 12 microns. The lumens of some tubules
appeared completely obliterated, due to the small tubule cross sec-
tions and high epithelium (Plate :1).

Excretory ducts were difficult to identify, but tubules located
in the inter-lobular connective tissue (Plate II) of the sebaceous
complexes were so designated on the basis of (1) their position, i.e.,

they were not situated within the sebaceous gland tissue as sebaceous

-25..

excretory ducts, and (2) because of the presence of leucocytes in
the lumens which was chuacteristic of the apocrine tubules. The
excretory ducts were lined by cuboidal epithelium of one or two
layers.

Krolling (1926) stated that there was one apocrine gland in the
anal sac which embryologically developed independently of any hair
follicle and in the post-natal animalbpened by means of a duct di-
rectly into the sac lumen (Plate IX). He contrasted this with
the other apocrine glands which developed, along with the sebaceous
glands, as outgrowths of hair follicle primordia. The hair fol-g
licles later degenerated and were not demonstrable in adult cats.
These apocrine glands were reported to open into the cisterns pre-
viously described for the sebaceous complexes. In the present study,
the openings of the individual apocrine glands into the sac lumen
were observed only infrequently. In one specimen, a situation simi-
lar to that described by Krolling appeared to occur, in which a duct
lined by several layers of epithelium seemed to open directly into
the anal sac and was not related to a sebaceous complex (Plate 1).
In other cases, ducts appeared to pass between the sebaceous lobules,
which was described by Krolling as the route of exit for some of
the apocrine glands associated withthe sebaceous glands, but they
were seen to empty directly into the anal sac lumen, not into the
sebaceous complex cistern (Plate 11). In many specimens apocrine
ducts were found in sebaceous complex stroma, but in no cases could
it be ascertained that the ducts emptied into the sebaceous cis-
term. The morphological differences pointed out by Krolling,

-26-

vis.: the wide variation seen in lumen diameters and epithelial
heights present in the "freelybopening" gland, in contrast to the
uniformity of the other apocrine glands, was not observed in the
present study. ‘Wide variations were noted, but did not appear con-

fined to one particular apocrine gland.

 

 

 

 

 

 

 

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Histochemistry

Staining with Oil Red 0 (Plate VII) showed lipid distribution
in the sebaceous complexes similar to that described by Krolling
(1926) for the anal sac, and by Montagna (1962) for human skin.
The contents of sebaceous gland ducts showed a strong reaction.
The peripheral cells of the individual alveolus reacted little,
or not at all. The central cells often gave a positive reaction,
although not as intensely as the contents of the lumens of the ducts.
Reaction to this stain did not occur elsewhere.

Glycogen precipitation, as demonstrated by the Best's carmine
technique, was seen to have a scattered distribution in the seba-
ceous cells, and was more constantly and regularly distributed in
the epithelial cells of the sebaceous complex ducts, the epithelium
of the anal sac lining and of the sac duct lining (Plate VIII). The
apocrine glands seemingly lacked glycogen.

An Alcian blue staining procedure was used to indicate the
presence of acid mucopolysaccharides. The luminal edges of the
apocrine glandular cells were stained slightly to moderately with
Alcian blue and the cytoplasm between the nuclei arxl the lumens oc-
casionally stained lightly. In some specimens the contents of the
lumens were stained. None of the anal sac tissue reacted to the
Alcian blue as intensely as did the goblet cell mucus of the rectal
mucosa. The sebaceous glands did not stain with Alcian blue.

The P.A.S. technique demonstrated polysaccharide distribution

similar to the glycogen distribution shown by the Best's carmine

-29-

technique, although the reactions were weak. This may have been be-
cause most of the specimens were fixed in.10% formalin, a procedure
reported to have a tendency to dissolve glycogen (Lillie, l9Sh).
In addition, some of the specimens exhibited droplets of P.A.S.
reactive material at the basal portions of the apocrine tubules.
Finely granular deposits of P.A.S.-reactive material also were found
at the basal portions of other apocrine tubules. The droplets may
have been associated with myoepithelial cells, whereas the finer de-
posits appeared to be in the glandular epithelial cells. The base-
ment membranes of the apocrine tubules reacted mildly with the P.A.S.
technique.

No conclusions were drawn relating the chemical nature of the
glands to the age or sex of the animals. The apocrine secretion
was believed to be mainly serous, instead of mucous, since the reac-
tion to Alcian blue was weak and inconsistent. The sebaceous con-
tribution was considered lipid in nature on the basis of the results
with Oil Red 0 stain. The remainder of the anal sac contents ap-
peared to be composed of cellular debris. Similar results were re-

ported by Montagna and Parks (l9h8) for the anal sacs of dogs.

SUMMARY AND CONCLUSIONS

Fifty-seven anal sacs were selected for study of gross, micro-
scopic and histo-chemical characteristics. Gross measurements were
made of entire sacs and microscopic measurements were made of sac
components as seen in cross sections of the organ.

These organs are paired, hollow, ovoid or spherical structures
about one centimeter in length, situated lateral to and on opposite
sides of the anus. Each sac was connected to the anal canal by a
narrow duct about three and one-half millimeters long which opened
at the level of the ano-cutaneous line. The sacs and anus, sur-
rounded by the external anal sphincter muscle, were embedded in fat.

The walls of the sacs were composed of white fibrous connec-
tive tissue in which were embedded up to nine ovoid complexes of se-
baceous glands measuring up to four millimeters in length. Coiled
tubular apocrine glands were present in the connective tissue between
the sebaceous complexes. The sacs were lined with keratinized, mod-
ified stratified squamous epithelium usually of two layers. Blood
vessels and nerves were observed in the connective tissue of the sac
and in the surrounding skeletal muscle. Leucocyte infiltration in
the connective tissue was comnon. The sac ducts also contained
white fibrous connective tissue, surrounded by skeletal muscle.
and lined by keratinized, stratified squamous epithelium. No glands

were observed in the walls of the ducts.

-30.

-31.

The sebaceous gland complexes consisted of masses of sebap
ceous alveoli separated by thin layers of connective tissue. These
glands were believed to be holocrine in nature, in that degeneration
of the sebaceous cells in the centers of the alveoli was thought to
be responsible for the formation of the beginnings of the sebaceous
duct systems. Each complex contained, in addition, a series of epi-
thelial-lined ducts terminating in a common cistern which opened ins
to the lumen of the anal sac. The apocrine glands were branched tus
bules lined by simple cuboidal to columnar epithelium. Myoepithelial
cells were between the epithelium and a basement membrane. The tup
bules appeared to be arranged as dense masses of coils. In some
cases the excretory ducts of the apocrine glands were embedded in the
connective tissue of the sebaceous complexes. The excretory duct
orifices were located near the sebaceous cistern Openings, as well as
at points between the sebaceous complexes. The tubules contained
leukocytes and cellular debris.

The excretory products of the anal sac consisted of a mixture
of fatty and serous materials and cellular'debris. The secretion
from the sebaceous alveoli consisted of lipid material, whereas the
apocrine gland secretion was believed to be serous. Also, keratin-
ized cells sloughed off from'the sac lining and cellular debris from
both types of glands were part of the sac contents.

The present study produced no evidence which could be used in
support of theories related to function. Both apocrine and sebap
ceous glands appeared active in immature and mature animals of both

sexes, and at various times of the year.

-32-

Perhaps investigation of the effects of hormones, breeding con?
dition, and removal of the sacs, on cats of known age would reveal
some facts about the function of the anal sacs as related to the

physiology and behavior of the animals.

LITERATURE CITED

Baker, Edward. 1962. Diseases and therapy of the anal sacs of
the dog. J.A.V.M.A. 1hlxl3h7-1350.

Bishop, Beverly. 1959. Reflex activity of external anal sphincter
of cat. J. neurophysiol. 22:679-692.

Crossmon, G. 1937. A modification of Mallory's connective tissue
stain with a discussion on the principles involved. Anat. Rec.

69333.38.

Cuyler, w. Kenneth. 1921-. Observations on the habits of the
striped skunk (Mephitis mesomelas varians). J. Mammalogy'
S3180-189e

 

Ellenberger,'w. 1911. Handbuch der Vergleichenden Mikroskopischen
Anatomie der Haustiere. Vol. III. Paul Parey, Berlin.

Ellenberger, W. and H. Baum. 19h3. Handbuch der Vergleichenden
Anatomic der Haustiere. Edited by Otto Zietzschmann, Eberhard
Ackerknecht, Hugo Brau. Springer-Verlag, Berlin.

Goldstein, D.J. 1961. On the origin and morphology of myoepithe-
lial cells of apocrine sweat glands. J. Invest. Born. 37:
301-309.

Gridley, M.F. 1957. Manual of Histologic and Special Staining
Technics. Armed Forces Inst. of Path. ‘Wash. D.C.

Hashimoto, Yoshijuke, Yasunobu Eguchi, and Akira Arakawa. 1963.
Histological observations on the anal sac and its glands in
a tiger. Japan Jour. Vet. Sci. 25:29-31.

Haynes, Julian.F. and A.C. Enders. 1961. The composition of the
anal glands of Dasypus novemcinctus. Amer. Jour. Anat. 1083
295‘3010

 

Rainer, Robert A. 195h. The gross anatomy of the digestive system
of the mink II. The midgut and the hind gut. Amer. Jour. Vet.
Res e 15 £91.97 0

Katsuna, Kazuo. 1959. A comparative histological study'of the
glands in the perineum in different female mammals. Acta
Medica (Jap.) 29:282-319.

-3h—

Krolling, Otto. 1926. Entwicklung, Bau und biologische Bedeutung
der Analbeuteldrusen bei der Hauskatze. Z. Anat. Entwicklungs-
gGSChe 82322-690

Lillie, ReD. 19Sh. Histopathologic Technique and Practical Histo-
chemistry. The Blakiston Division. MbGrawbHill Book Co.,
New York.

Malawitz, T.D. and E.M. Smith. 1955. A nuclear stain employing
dilute Harris hematoxylin. Stain.Techn. 30:311.

McManus, J.F.A. and Robert W. Mowry. 1960.‘ Staining Methods Histo-
logic and Histochemical. Paul B. Hoeber, Inc.

Martin, Paul. 1923. Iehrbuch der Anatomie der Haustiere. Vol. Iv.
Schickhardt & Ebner, Stuttgart.

Mbntagna, William. 1962. The Structure and Function of Skin.
Academic Press. New York.

MOntagna, William and Harold Parks. l9h8. A histochemical study of
the glands of the anal sac of the dog. Anat. Rec. 100:297-

317.

Parkes, A.S. 1960. The role of odorous substances in mammalian re-
production. J. Reprod. Fertility. 12312-3lh.

Reighard, Jacob and H.S. Jennings. l9h0. Anatomy of the Cat.
Henry Holt and Co., New York.

Schaffer, Josef. l9h0. Die Hautdrusenorgane der Saugetiere mit
besonderer Berucksichtigung ihres histologischen Aufbaues und
Bemerkungen uber die Proktodaaldrusen. Urban.&.Schwarzenberg,
Berlin.

Schwartz, Charles W. and Elizabeth R. Schwartz. 1959. The Wild
Mammals of Missouri. Univ. of Missouri Press and Missouri
Conservation Commission.

Titkemeyer, Charles. 1958. Applied anatomy of the perineal region
of the dogs MeSeUe Vet. 183162-1614.

Trautmann, A. and J. Fiebiger. L957. Fundamentals of Histology of
Domestic Animals. (Translated and.revised by R.E. Habel and E.L.
Biberstein.) Comstock Publishing Assn., Ithaca, New York.

Anal sacs exposed by dissection, ventral view.

About 2.21.
l.
2.
3.
h.
5.

Plate I

Anal sacs

Pubic symphysis
Urethra

Obturator foramen

Ventral surface of tail

Fresh Specimen.

 

“an“

———q

 

 

Plate II

Anal sac with duct opening into anal canal near Linea ano-

 

cutanea, cross section. Harris' hematoxylin and eosin stain.

25X.

1.
2.
3.
h.
5.
6.
7.

Sec lumen
Keratinized material in.lumen of sec duct

Linea ano-cutanea

 

Apocrine glands
Sebaceous complex
Skeletal muscle

Circumanal glands

 

I. In

 

Plate III

Pacinian corpuscle in connective tissue of sac wall.
hematoxylin and eosin. lhBOX.
l. Pacinian corpuscle

2. Keratinized epithelium of sac lining

Harris'

 

 

 

- fiM-A——-HF—-q H‘“,Hr

 

Plate IV

Reticular tissue appearing as black fibers surrounding seba-
ceous alveoli and in the connective tissue. Silver technique
and Nuclear Fast Red stain. 2hOX.

1. Sebaceous alveoli

2. Sebaceous complex cistern

3. Epithelium of sac lining

 

Plate V

Sebaceous gland complex, longitudinal section. Mallory's tri-
chrome stain. lOSX.

1. Sebaceous alveoli

2. Beginnings of sebaceous ducts

3. Sebaceous ducts

h. Anal sac lumen

5. Apocrine tubules

6. Skeletal muscle

7. Connective tissue

 

Plate VI

Portion of sebaceous gland complex showing cellular disinte-
gration leading to duct formation. Mallory's trichrome stain.
5191.

1. Areas of cellular disintegration

2. Sebaceous alveoli

3. Sebaceous complex ducts

 

-

WAMA A

‘—

——_—-—‘_ —\ —‘__. “fl“aa— '- ~_‘n —— ,—

 

Plate VII

Portion of sebaceous gland complex showing fat distribution.
011 Red 0 stain. 1501.
1. Sebaceous ducts containing fat

2. Sebaceous alveoli containing fat

 

Plate VIII

Portion of sebaceous gland complex showing glycogen distribu-
tion. Best's carmine stain. 525x.
1. Glycogen deposits in sebaceous alveoli

2. Glycogen deposits in sebaceous ducts

 

Plate IX

Apocrine duct opening into sac lumen near sebaceous gland

complex. Mallory's trichrome stain. 314M.

1.

2.
3.
h.
5.

Apocrine gland duct containing leucocytes opening
into sac lumen

Sac lumen

Epithelium of sac lumen

Sebaceous alveoli

Apocrine gland duct containing leucocytes passing

through connective tissue of sebaceous gland complex

.___———.4_—;.——-——..— '.—\_—_—_‘q_— — qfimr—‘_F~“——Ffi_—.—_—kl—a

‘-—-."“

 

Plate 1

Apocrine gland duct opening into sac lumen. Mallory's tri-
chrome stain. 335K.

1. Apocrine gland duct

2. Apocrine tubules

3. Connective tissue

h. Epithelium of sac lining

5. Keratinized material in lumen of sac

c."- I v .
N‘. .

. if, L“ ’ " a . Y

a ‘:§&’\{;4... gow... a 7."? .‘

‘ -. f a“ new?“
‘ .- ~ f~ “($13?" ‘.

 

Plate XI

Apocrine gland tubules. Harris' hematoxylin and eosin .

1325!.
l.

2.

3.

Glandular epithelium
Nuclei of myoepithelial cells

Leucocytes

fl‘m‘fi’.

_,__... —‘M J

 

-56—

Plate III

Apocrine gland tubules. Harris' hematoxylin and eosin. thX.
1. Apocrine tubules containing leucocytes
2. Portion of sebaceous complex

3. Skeletal muscle

 

-m-

Plate XIII

Reticular tissue seen as black fibers surrounding apocrine
tubules and as irregularly arranged fibers in the connective
tissue stroma between the apocrine tubules. Silver technique

and Nuclear Fast Red stain. ZhSX.

 

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WIIHIGHIIII |
3

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