ANS 3319C Reproductive Physiology and Endocrinology Lab Male

Transcription

ANS 3319C Reproductive Physiology and Endocrinology Lab
Male Reproductive Anatomy
Objectives
1) To learn the anatomical structures of the male reproductive tracts of farm animals.
2) To learn the functional significance of the anatomical parts of the male reproductive tract.
3) To learn how the different anatomical parts of the reproductive tract function as a unit from the production of
sperm to its eventual ejaculation from the penis in farm animals.
The male reproductive organs consist of: a) paired testes, b) epididymides, c) efferent ducts, d) ampullae (absent
in some species), e) paired seminal vesicles, f) prostate gland, g) paired bulbo-urethral (Cowper's) glands, and h)
penis.
The seminal vesicles, prostate, and bulbo-urethral glands discharge secretions into the pelvic urethra, which mix
with spermatozoa and fluids secreted by the testes, epididymides, and vas deferens, and for this reason they are
often termed the accessory sex glands.
Please refer to “Pathways to Parturition and Pregnancy” for the figures cited in this review.
I. SCROTUM
The scrotum is present in all domestic animals and is an out-pouching of skin from the abdominal region and
encloses the testes. By the last third of gestation in domestic animals, the testes are normally located in the
scrotum (Figures 3-3, 3-4, 3-5, 3-6, 3-7, 3-8). Failure of the testes to descend into the scrotum results in a
condition known as cryptorchidism (Figure 4-8). If both testes fail to descend (bilateral cryptorchidism) it results in
sterility. A unilateral cryptorchid has a single descended testis; they are fertile but there is a tendency for this
condition to be inherited. Males possessing this trait should not be used for breeding.
The scrotum consists of five layers (Figures3-2, 3-14, 3-25) from outside to inside as follows:
1) An outer layer, the skin or epidermis, is heavily populated with sweat glands to assist in maintaining proper
testicular temperature.
2) The tunica dartos consists of fibro-elastic tissue and smooth muscle, which is connected closely with the
tunica vaginalis at the bottom of the scrotum. The scrotum consists of two pouches, which contain a testicle.
The tunica dartos acts as a thermoregulator by contracting to draw the testes close to the abdomen when
cold and relaxing when the testes are warm.
3) The stratum subdarticum is a loosely woven layer of connective tissue between the tunica dartos and
tunica vaginalis-parietal layer. This tissue allows the testes extraordinarily free mobility in an upward and
downward direction.
4) The tunica vaginalis-parietal layer (lines the scrotum) is continuous with the peritoneum.
5) The tunica vaginalis-visceral layer (covers the testis) is continuous with the peritoneum.
A.
BULL - The scrotum is long and pendulous and has a well-marked neck when not contracted. It is
covered with short hairs with four (sometimes two) rudimentary teats in front of it.
B.
RAM - The scrotum possesses the same general characteristics as the bull.
C.
BOAR - The scrotum is situated only a short distance from the anus and is less distinctly separated
from the surrounding parts than in other animals (less saccular).
D.
STALLION - The scrotum is globular in form but is often asymmetrical because of the larger size of one
testicle, usually the left one. The scrotum is not located as far forward as in the bull.
E.
DOG - The scrotum is similar to the boar and located in the same general area.
F.
CAT – The scrotum is located between the anus and the penis unlike the other animals studied.
II. TESTIS (Plural TESTES)
The paired organs are usually ovoid or walnut shaped. They are the primary organs of reproduction in the male.
The testes are fixed in the sack of the tunica vaginalis. They consist of a series of distinct duct systems
ANS 3319C Reproductive Physiology and Endocrinology Lab - Male Reproductive Anatomy
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(seminiferous tubules), which open into a common excretory channel (rete testis). The testes are enclosed in a
series of membranous capsules as follows (Figures 3-14, 3-15):
1)
The tunica vaginalis is a thin white membrane, which is a continuation or evagination of the abdominal
peritoneum extending through the inguinal canal to the distal end of the scrotum. It consists of two layers:
a) parietal layer, which lines the scrotum and therefore is part of the scrotum, and the b) visceral layer,
which covers the spermatic cord, testis, and epididymis.
2)
The tunica albuginea lies directly beneath the tunica vaginalis and encloses the testis proper. It is a
dense, thick connective tissue capsule. The inner surface consists of many tortuous blood vessels.
When the tunica albuginea is cut, the gland substance or parenchyma (which is soft and yellowish in color)
protrudes. The consistency of the testis is usually turgid. On a cross-sectional view of the testis, the mediastinum
lies in the middle. It encloses the rete testis (the cavernous openings through which sperm pass). The
seminiferous tubules (Figure 3-15) are lined with germinal epithelium that produces spermatozoa. Intermixed
among the germinal epithelial cells are the large Sertoli cells (Figure 3.16), which provide nutrition for the
developing sperm. Between the seminiferous tubules are the islands of interstitial cells or Leydig cells (Figure
3-16) which secrete the male sex hormone (testosterone). The seminiferous tubules connect into an area of
cavernous-like tissue with wide anastsmosing channels known as the rete testis (Figure 3-15). Leading from the
rete testis are 6 to 12 efferent ducts (Figure 3-15) (ducti efferentia) which pierce the tunica albuginea at a small
area (about a centimeter in diameter) at the dorsal (anterior) part of the testis and enter the head of the epididymis.
A. BULL - The testes are oval in shape and weigh between 250 and 500 grams. The long axis of the
testis is vertical. The seminiferous tubules are about 5,000 meters in length.
B. RAM - The testes are oval in shape and weigh between 200 and 400 grams. The testicles are larger in
proportion to the size of the ram than in the bull.
C. BOAR - The testes are very large and rounded (oval) in shape with the long axis (distal end) directed
upward and backward. Each testis weighs between 500 and 800 grams. Cryptorchidism is fairly
common in pigs.
D. STALLION - The testes are oval in shape. Each testis weighs between 200 and 300 grams. The long
axis is nearly horizontal with the proximal end forward. However, when the testes are retracted the
long axis becomes nearly vertical.
E. DOG & CAT – The testes are small and oval in shape with the long axis long axis (distal end) directed
upward and backward similar to the boar.
III. EPIDIDYMIS (Plural EPIDIDYMIDES)
The epididymis (Figures 3-14, 3-15, 3-18; Table 3-1) is composed of a single, tortuously coiled tubule (ductus
epididymis) that is essential for the storage, maturation, and transport of sperm. It has a smooth muscular coat,
which aids in moving the sperm with peristaltic waves toward the vas deferens. It is connected to the testis by
fibrous tissue. The proximal end of the epididymis is called the head or caput epididymis. The intermediate
segment is called the body or corpus epididymis, and the enlarged distal end is called the tail or cauda
epididymis. The tail is continuous with the ductus deferens (or vas deferens) and serves as the major preejaculatory storage location for sperm.
A.
BULL - The head is dorsal and the tail is ventral to the testis. The ductus epididymis is approximately
35 meters long. In the coiled condition, the epididymis is about 20 cm long.
B.
RAM - The epididymis possesses the same general characteristics as the bull.
C.
BOAR - The epididymis is very large (especially the tail). The tail of the epididymis is dorsal and the
head ventral.
D.
STALLION - The tail of the epididymis is caudal, the body dorsal, and the head cranial.
E.
DOG & CAT - The tail of the epididymis is dorsal and the head ventral similar to the boar.
IV. SPERMATIC CORD
The testis is suspended in the scrotum by the spermatic cord (Figures 3-2). The cord extends from the
abdominal inguinal ring to its attachment at the dorsal (anterior) end of the testis. It is composed of the following
structures, which are carried down by the testis in its migration through the inguinal canal from the abdominal cavity
to the scrotum near the time of birth:
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1)
A single spermatic artery is tortuously coiled dorsal to the testis. The two spermatic veins form a plexus
of veins around the spermatic artery. Collectively, the veins and the artery form the pampiniform plexus
(Figure 3-9, 3-10), which is located in the spermatic cord. Counter current heat exchange between the
warmer arterial blood and cooler venous blood cools the arterial blood before it enters the testis to keep the
temperature in the testes at 34oC.
2)
The lymphatics, which accompany the veins.
3)
The autonomic nerves around the vessels in the spermatic cord.
4)
The ductus deferens or vas deferens.
5)
The internal cremaster muscle.
6)
The tunica vaginalis propria.
7)
The external cremaster muscle, which attaches laterally on the tunica vaginalis-parietal layer down to the
level of the caput epididymis.
A. BULL - The spermatic cord is 20 to 25 cm long. Possesses a well-developed external cremaster muscle
(especially posteriorly).
B. RAM – Very closely resembles the spermatic cord of the bull.
C. BOAR - The spermatic cord is very long in proportion to the size of the animal and the position of the
testis (20 to 25 cm).
D. STALLION - The spermatic cord resembles that of the bull, except that the external cremaster is less
developed and the spermatic cord is shorter, being only 10 to 12.5 cm long.
E. DOG & CAT - Similar to the boar, in that the spermatic cord is very long in proportion to the size of the
animal and the position of the testis.
V. DUCTUS DEFERENS (VAS DEFERENS) and AMPULLA
The ductus deferens (Figures 3-3, 3-4, 3-5, 3-6, 3-7, 3-8) is simply a continuation of the epididymis extending
from the tail of the epididymis to the pelvic urethra. Its primary function is to transport spermatozoa from the
epididymis to the urethra. The wall of the ductus is thick and heavily muscled while the lumen is very small. The
ductus deferens passes upward parallel to the testis and body of the epididymis into the spermatic cord, through
the inguinal canal, and to the pelvic urethra, where the wall becomes thickened and folded to form a structure
known as the ampulla (Figures 3-4, 3-5, 3-19, 3-20). The thickening of the duct is due to abundant embedding of
glands in the wall of the ductus deferens. The ampulla may serve as a limited storage place for spermatozoa. The
ampullae narrow and pass under the body of the prostate to empty into the colliculis seminalis or cranial portion
of the pelvic urethra. In some species, ejaculatory ducts may be formed by a union of the ductus deferens and the
proximal portion of the duct of the seminal vesicle.
A.
BULL - The walls of the ductus deferens are not as thick as in other species, but still possess a firm cordlike character. On reaching the bladder, the two ducts are close together for a distance of about 10 cm
where they form very distinct ampullae about 16 cm long and 1 to 1.5 cm in diameter. The ducts pass
under the body of the prostate and end just in front of the ducts of the seminal vesicles as slit-like
openings on top of the colliculis seminalis.
B.
RAM - The ductus deferens possesses the same general characteristics of the bull.
C.
BOAR - The ductus deferens is very flexible in the testicular part and is closely attached to it by the tunica
vaginalis. They lack a distinct ampulla.
D.
STALLION - The ductus deferens has a firm cord-like character. Until it enlarges to form the ampulla, the
duct is of uniform diameter (about 0.5 cm). The ampulla is about 15 to 20 cm long and 2 to 2.5 cm in
diameter. In geldings, the ampulla are not as conspicuous.
E.
DOG & CAT – They lack a significant ampulla.
VI. SEMINAL VESICLES (VESICULAR GLANDS)
The seminal vesicles (vesicular glands) (Figures 3-3, 3-4, 3-5, 3-6, 3-7, 3-8, 3-19, 3-20) are paired accessory
glands located on the floor of the pelvis, lateral to the ampulla or ductus deferens and the neck of the bladder.
They secrete a fluid that adds volume and nutrients to the semen. Each of the vesicles connects with the pelvic
urethra in the region of the bladder by means of a main excretory duct opening into the colliculis seminalis. In
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some species, the excretory duct at its opening unites with the ductus deferens forming together, on both sides, the
ejaculatory ducts. These glands do not store sperm as once thought.
A.
BULL - The seminal vesicles are markedly lobulated and are the largest of the accessory glands in the
bull. In adult bulls, they average 12 to 15 cm in length. Each gland may contain 10 to 15 ml of fluid. The
seminal vesicles are the site of fructose synthesis and secretion, which serves as the primary energy
source for ejaculated spermatozoa.
B.
RAM - The seminal vesicles are very similar to the bull except smaller. Each gland is between 5 to 6 cm
long and 2 to 3 cm wide.
C.
BOAR - The seminal vesicles are exceedingly large, extending into the abdominal cavity. They are threesided, pyramidal masses, 12 to 15 cm long, 5 to 8 cm wide, 4 to 5 cm thick, and weigh from 150 to 250
grams each. The vesicle has a single excretory duct formed from 6 or more large, thin-walled ducts. The
two ducts, one from each vesicle, open closely together, near the summit of the small colliculis seminalis.
D.
STALLION - The seminal vesicles are elongated pyriform-shaped sacs, which measure 15 to 20 cm long
and 5 cm in diameter. The excretory duct opens in common with the ductus deferens on the side of the
colliculis seminalis.
E.
DOG & CAT – do not have vesicular glands.
VII. PROSTATE GLAND
The prostate (Figures 3-3, 3-4, 3-5, 3-6, 3-7, 3-8, 3-19, 3-20) is a single, compound tubulo-alveolar gland. Three
varieties can be recognized in domestic animals. First, the prostate may form definite lobes located on or around
the neck of the bladder or cranial portion of the pelvic urethra. Secondly, the gland may consist only of disseminate
or scattered parts consisting primarily of urethral glands extending along the pelvic urethra. Thirdly, the gland may
consist of both the lobular and disseminate parts in some species. The gland is rather firm in consistency and
secretes a slightly alkaline fluid, which is largely responsible for the characteristic odor of semen.
A. BULL - The prostate is pale yellow in color and consists of two parts which are continuous with each other.
At the anterior end of the pelvic urethra is the distinct body of the prostate, which measures 3 to 4.5 cm in
width and 1 to 1.5 cm in length. The hidden disseminate prostate surrounds the pelvic part of the urethra.
The disseminate prostate is concealed by the urethral muscle and often escapes notice, but it is quite
evident on cross-section. The prostatic ducts open into the pelvic urethra.
B. RAM - The prostate is entirely disseminate and diffused over a large portion of the pelvic urethra.
C. BOAR - The prostate is similar to the bull in that it consists of two parts. The body, which is about 5 cm
long and 2.5 cm wide, can often be partially concealed by the seminal vesicles. The disseminate prostate
forms a layer which surrounds the pelvic urethra and is covered by the urethral muscle.
D. STALLION - The prostate is a lobulated gland consisting of two lateral lobes connected by a thin transverse
isthmus. The lobes are somewhat prismatic in form and are close to the seminal vesicles.
E. DOG – Only accessory gland in the dog and is situated around the neck of the bladder.
F. CAT – Prostate consist of four lobes that are dorsal to the pelvic urethra
VIII. BULBOURETHRAL GLANDS (COWPER’S GLANDS)
The Copwer's glands (Figures 3-3, 3-4, 3-5, 3-6, 3-7, 3-8, 3-19, 3-20) are paired glands lying on either side of the
pelvic urethra near the ischial arch. They are generally ovoid in shape and much smaller than the seminal vesicles,
with certain exceptions (the pig). They often escape notice since they are embedded in and covered by a thick
layer of dense fibrous tissue, and also partially by the urethral and the bulbo-cavernosus muscles. The bulbourethral glands secrete an alkaline fluid.
A. BULL - The Cowper's glands each weigh between 1 to 13 grams and measure 2 to 3 cm in diameter. They
are covered completely by the bulbo-cavernosus muscle. The excretory ducts in each gland unite into a
single duct. They open into the pelvic urethra at the ischial arch.
B. RAM - The Cowper’s glands are smaller than those in the bull but present the same general characteristics.
C. BOAR - The Cowper's glands are very large (12 cm long and 3 cm diameter in the mature animal and look
like hot dogs) and are composed of very dense tissue. They are cylindrical in shape and lie on either side
of and upon the posterior two-thirds of the pelvic urethra. The urethral muscle partly covers their lateral
surfaces. They produce the gel found in boar semen.
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D. STALLION - The Cowper's glands are ovoid in form and measure about 4 cm in length and 2.5 cm in width.
E. DOG – does not have bulbourethral glands.
F. CAT – bilobed bulbourethral glands that are just posterior to the urethral muscle.
IX. URETHRA
In the male, the urethra is the excretory canal for both urine and semen. It is a long tube extending from the
bladder to the glans penis. It passes backward on the floor of the pelvis, turns sharply ventral around the ischial
arch, and passes forward as a part of the penis, enclosed in the corpus cavernous urethra. It is divided into three
parts: 1) pelvic urethra, 2) ischial urethra, and 3) extra pelvic or penile urethra.
1)
The pelvic urethra extends from the neck of the bladder to the bulbo-urethral glands or to the ischial arch.
The greater part of the organ is made up of a powerful muscle (urethral muscle), which almost entirely
encloses the mucosal tube. By its forcible contraction it plays an important role in ejaculation of semen and
evacuation of the last of the urine during micturition. Upon dissection of the organ, ventrally in the midline, a
raised prominence called the colliculis seminalis may be seen dorsally just posterior to the neck of the
bladder. The colliculis seminalis consists chiefly of cavernous tissue, which during ejaculation is assumed
to be able to close the bladder and thus prevent a simultaneous discharge of urine. In association with the
colliculis seminalis are the two ejaculatory ducts, which are the common openings for both the ductus
deferens and the seminal vesicle.
2)
The ischial urethra designates that part of the urogenital canal which extends from the Cowper's glands,
bending around the ischial arch to the area where the two crura penis meet, and lying neither in the pelvic
cavity nor belonging to the penis proper. It represents that part of the urethra, which is covered by the
bulbo-cavernosus muscle. The cavernosus tissue in this area is slightly thicker than in the pelvic urethra.
This area of cavernosus tissue is known as the bulb of the urethra. The bulbo-cavernosus muscle is a
continuation of the urethral muscle and extends from the ischial arch to near the glans penis (in some
species). At the root of the penis it is thickest and forms a complete layer of circular fibers enclosing the
corpus cavernous urethra. Beyond this point it diminishes very gradually in thickness until it terminates on
the tunica albuginea of the corpus cavernous penis. Its action is to empty the extra-pelvic part of the urethra
and to ejaculate sperm.
3)
The extra pelvic urethra passes between the two crura of the penis and runs along the ventral surface of
the corpus cavernous penis opening on the glans penis. It is enclosed by the corpus cavernous urethra and
the bulbo-cavernosus muscle. The bulb of the urethra is the start of the corpus cavernous urethra. The
corpus cavernous urethra contributes to the formation of the glans penis. Thus, cavernosus tissue in
varying amounts surrounds the urethral canal throughout its entire length.
A.
BULL - The urethral muscle encloses the tube ventrally and laterally. Ventrally, the muscle is 2 to 2.5
cm thick. The colliculis seminalis is a rounded prominence about 2.5 cm long. On it are the two
ejaculatory ducts about 5 mm deep situated very closely together. The ischial urethra has a thick
tunica albuginea enclosing highly developed cavernous tissue. The bulbo-cavernosus muscle is only
15 to 20 cm long and is covered by a layer of connective tissue. It is divided into two lateral halves,
except at its origin.
B.
RAM - The terminal part of the penile urethra projects about 3 to 4 cm beyond the glans penis forming
a free filliform appendage or processus urethrae. The remaining features of the urethra are very similar
to those of the bull, except that they are smaller.
C.
BOAR - The pelvic urethra is covered by the urethral muscle. The penile part is of small caliber and is
surrounded by erectile tissue, which does not extend to the extremity of the penis.
D.
STALLION - The pelvic urethra is 10 to 12 cm long and at its origin it is not distinguishable from the
neck of the bladder in size or structure. Beyond the prostate it dilates to a width of 5 to 6 cm and
contracts again between the bulbo-urethral glands. Numerous urethral glands are present in the pelvic
urethra.
E.
DOG – similar to farm animals in the structures of the urethral area including the crus penis, bulbo- and
ischiocavernosus muscle as well as a retractor penis muscle.
F.
CAT – very small urethral area but has a crus penis, ischiocavernosus muscle, and a prominent
bulbospongiosis muscle.
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X. PENIS
The male organ of copulation consists of three parts: 1) the attached portion or root, 2) the main portion, the shaft
or body, and 3) the enlarged free end, the glans penis (Figures 3-3, 3-4, 3-5, 3-6, 3-7, 3-8, 3-21, 3-22). It extends
forward from the ischial arch to the umbilical region on the abdominal wall and is supported by the penile
connective tissue and skin. The penis is composed essentially of erectile tissue which encloses the penile urethra.
The root of the penis is formed by two crura (the backward extensions of the corpus cavernous penis) on either
side of the ischial arch. At its origin, it is attached to the pelvic bone by two strong suspensory ligaments. The
body of the penis begins at the junction of the crura and constitutes the bulk of the organ. It is composed primarily
of the large corpus cavernous penis, which is enclosed by a thick fibrous capsule, the tunica albuginia. Ventral to
this is the corpus cavernous urethra, the smaller structure surrounding the extra-pelvic urethra. These two corpora
are very spongy in character and are divided into many spaces that can be regarded as greatly enlarged capillaries.
They are continuous with the veins of the penis. Erection results from distention of the corpus cavernous penis with
blood. The glans penis is the enlarged free end of the penis arising from the corpus cavernous urethra. The skin
covering the glans is thin, glandless, and richly supplied with nerves and special nerve endings. The glans penis is
situated in a cutaneous pouch, called the prepuce.
There are two important muscles associated with the penis. The ischio-cavernosus muscle and the erector penis
muscle at the root of the penis. It is a short, strong, paired muscle which is inserted on the crura and the adjacent
part of the body of the penis. During erection it pulls the penis against the ischial arch, thus compressing the veins
of the penis and preventing the backflow of blood during erection. This forced blood through the crura, which are
the origin of the corpus cavernous penis. Increased blood pressure makes the penis turgid and erect. The
retractor penis muscle is a smooth muscle, which arises on the vertebrae, divides, and meets again under the
anus. The muscle passes along the body of the penis, becoming attached to the tunica albuginea of the penis. Its
action is to draw the penis back into the sheath after erection subsides.
A. BULL - The penis is cylindrical in form and is characterized by the S-shaped curve or sigmoid flexure. In
the adult bull, the penis is about 95 cm (80 to 100 cm) long from the root to the tip of the glans. The penis
enlarges very little during erection. In the erect state, the penis is seldom over 2.5 to 3.5 cm in diameter.
During erection and protrusion, the sigmoid flexure straightens out, thus affording an increase of about 30
cm in length. The glans penis is about 8 cm long and its extremity is pointed and twisted to the left.
B. RAM - The glans penis is 5 to 7.5 cm long and the diameter of the penis is relatively small, as in the bull.
The urethra lies in a groove on the ventral surface of the corpus cavernous penis and forms the urethral
process at its terminal ending. Otherwise the penis resembles that of the bull.
C. BOAR - The penis is similar to that of the bull. The anterior portion of the glans is spirally twisted to the left
(ie, corkscrew) especially at erection. In the adult boar, the penis is about 45 to 50 cm long.
D. STALLION - The penis has a large amount of erectile tissue. It is more or less cylindrical in form. In the
non-erect state it is about 50 cm long and 2.5 to 5 cm in diameter. Of this, about 15 to 20 cm is free in the
sheath. Upon erection it increases 50% or more in both length and thickness, while the glans penis
enlarges three or more times. There is no sigmoid flexure in the stallion. The retractor penis muscle is
not as strong as in the bull and is loosely attached to the ventral surface of the penis.
E. DOG – The penis is similar to farm animals in that it extends/contracts via the retractor penile muscle and
has corpus cavernosum tissue. However, it is significantly different in that it has a bulbous glandis on the
anterior end of the penis, which engorges with blood at erection and forms a bulb that allows for the
“copulatory tie” at mating. The penis is also equipped with an OS penis located in the end of the penis.
The penis is also flexible allowing for the penis to bend at almost a 90° angle during the “copulatory tie”.
F. CAT - The cat has a penis unlike the rest of the farm animals. It is very small and extends out the posterior
of the cat below the anus. It also has penile spines that are thought to be important in stimulation of the
vagina during the mating process. The contact between the spines and the vagina are thought to be
responsible for the “loud vocalization” made by the queen during mating.
XI. PREPUCE and SHEATH
The prepuce is a double invagination of skin which contains and covers the free, or prescrotal, portion of the penis
when not erect and covers part of the body of the penis behind the glans when the penis is erect. The external
opening is called the preputial orifice. The lining of the prepuce is a freely movable membrane or modified skin that
is attached firmly only at the glans penis and at the preputial orifice. Numerous preputial glands are present. The
sheath is the layer of skin that houses and protects the penis when it is not extended.
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A. BULL - The prepuce is very long (35 to 40 cm) and narrow (3 cm in diameter). The preputial orifice is
about 5 cm behind the umbilicus. The lining membrane forms longitudinal folds.
B. RAM - The prepuce is similar to that of the bull, but is relatively smaller.
C. BOAR - The prepuce has a very narrow orifice, while the cavity is very long and is partially divided by a
circular fold into a posterior narrow part and a much wider anterior part. In the dorsal wall of the wide part,
there is a circular opening, which leads into a cul-de-sac, the preputial diverticulum. The diverticulum may
become filled with decomposing urine and macerated epithelium, which has a very characteristic,
unpleasant odor.
D. STALLION - The internal layer of the preputial cavity passes backward about 15 to 20 cm lining the cavity
of the external part of the prepuce, and is then reflected forward until it approaches the orifice where it is
again reflected backward. Thus, a secondary tubular invagination (prepuce proper) is formed in which the
anterior penis lies. The opening between the cavities is called the preputial ring.
E. DOG – Does have a small prepuce and sheath that protects the end of the penis. There is small orifice at
the end of the sheath from which the penis extends.
F. CAT – No significant prepuce and sheath like farm animals. A very small orifice exists below the anus from
which the penis protrudes.
Figure 3-4. Sagittal view of the bull reproductive tract anatomy.
Figure 3-4. Sagittal view of an excised bull reproductive tract. A - ampulla; BP - body of prostate; CM - cremaster
muscle; CP - crus penis; DD - ductus deferens; GP - glans penis; IcM - ischiocavernosus muscle; PS - penile shaft;
RPM - retractor penis muscle; SF -sigmoid flexure; TE -tail of epididymis; T -testis; UM -urethralis muscle; UB -urinary
bladder; VG -vesicular gland.
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Figure 3-5. Sagittal view of the stallion reproductive tract anatomy.
Figure 3-5. Sagittal view of an excised stallion reproductive tract. A - ampulla; BP - body of prostate; CM - cremaster
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Figure 3-6. Sagittal view of the boar reproductive tract anatomy.
Figure 3-6. Sagittal view of an excised boar reproductive tract. A - ampulla; BP - body of prostate; CM - cremaster
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Figure 3-7. Dog reproductive tract
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Figure 3-8. Cat male reproductive tract
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Figure 3-2. The spermatic cord and its components
Figure 3.2a (Extra not from textbeeok). The pampiniform plexus - a countercurrent heat exchanger
and testosterone exchanger.
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Figure 3-14. Excised testicles from the bull, boar, and stallion. The parietal tunica vaginalis has been incised and
reflected away from the testis. CM – cremaster muscle; DD – ductus deferens; EB – epididymal body; EH – epididymal
head; ET – epididymal tail; PP – pampiniform plexus; PTV – parietal tunica vaginalis; T – testis; TA – tunica albuginea;
VTV – visceral tunica vaginalis.
14
Figure3-14 (Extra not from text book). The anatomy of an epididymis, with descriptions of sperm
maturation by region of epididymis.
15
Figure 3-15. Excised testes from a boar and bull which have been incised longitudinally to expose the testicular
parenchyma and mediastinum. Arrows denote the direction of flow of spermatozoa and fluids toward the efferent
ducts (not in photos) and the head of the epididymis. EH – epididymal head; ET – epididymal tail; M – mediastinum;
PP – pampiniform plexus; TP – testicular parenchyma.
Figure 3-15. Schematic illustration of the internal testis anatomy, scrotum, the connective tissue supporting
structures, and the tubular pathway of the typical mammalian testis.
16
Figure 3-16. Anatomy of the seminiferous tubule, showing the relationship of the germ cells to the adjacent Sertoli
cells and the blood-testes-barrier that forms between the basal and interstitial compartments.
17
Figure 3-19. Dorsal view of the accessory sex glands in the bull and stallion.
18
Figure 3-20. Dorsal view of the accessory sex glands in the boar, dog, and cat.
19
Figure 12. Distal end of a bull penis. GP - glans penis; F - free end of penis.
Figure 3-21. Photographs of the distal ends of penises of a boar, bull, stallion, and ram. F – free end of penis; GP –
glans penis; PF – preputial fold; UP – urethral process.
Figure 3-21. Cross-sections of the penile shafts of a stallion and a bull. BsM - bulbo-spongiosus; CC - corpus
cavernosum; CS - corpus spongiosum; DEC - dorsal erection canals; RPM - retractor penis muscle; T - trabeculae
(from tunica albuginea); TA - tunica albuginea; U - urethral process.
20
Figure 3-22. Glans penis of dog, Tom, and Alpaca and the penile shaft of the dog.
21
Notes
22

ANS 3319C Reproductive Physiology and Endocrinology Lab Male

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