MALE REPRODUCTIVE ORGANS

2019

THE MALE GENITAL SYSTEM

It consists of :

• Paired testes.
• Convoluted duct of the epididymis, the deferent duct and the urethra.
• The accessory glands:

a- Vesicular

b- Prostate

c- Bulbourethral

d- Ampullary

• Penis
• Scrotum and Prepuce

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�EPIDIDYMIS

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• Is elongated structure that firmly attached along the testis and consists of the coils of the elongated convoluted tubules, which are held together by connective tissue .

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• It can be divided into three parts:

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1-head.

2- body.

3-tail.

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The tail of the epididymis

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• is the continue of the epididymal ducts.
• attached to the caudal extremity of the testis by the proper ligament of the testis .
• and to the vaginal process by the ligament of the tail of the epididymis.
• This ligament extends fibers into the deep layer of the scrotum as the scrotal ligament
• The duct of the epididymis emerges at its tail and continues as the ductus deferens.

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�DEFERENT DUCT (DUCTUS DEFERENS)

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• is the direct continuation of the duct of the epididymis, originates as the undulating part of the tail of the epididymis and gradually straightens as it passes along the medial border of the testis.

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• Protects and supports the testes

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• Dual chambered pouch Separated by a septum into right and left halves

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• Each half containing a testis, epididymis, and the distal portion of the spermatic cord

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• The scrotal septum encloses the testes separately and is marked externally as a groove.

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• The scrotal skin is usually hairless, except in the cat and certain breeds of sheep, where it is covered in hair.

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• It has a generous supply of both sweat and sebaceous glands and adheres firmly to the underlying tunica dartos.

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Scrotum

INVESTMENTS OF THE TESTIS

The investments of the testis not only cover the testis, the epididymis and parts of the spermatic cord, they also are moulded around these organs.

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The different layers of the testicular investments correspond to the layers of the abdominal wall

scrotum:

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1. External skin.

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• Fibromuscular subcutaneous layer (tunica dartos)

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• Double-layered external spermatic fascia, detachments of the abdominal fasciae.

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• Cremaster muscle, a detachment of the internal oblique muscle of the abdomen, along with its fascia.

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vaginal process :

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5. Internal spermatic fascia, Visceral and parietal layer of the vaginal tunic.

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Investments of the testis

They are the following layers:

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• The external spermatic fascia is detached from the deep and the superficial fascia of the abdomen at the scrotum and is divided into a deep and a superficial layer.

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• It is of clinical significance, since it facilitates castration by a closed technique, whereby the vaginal tunic is ligated with the blood vessels and ductus deferens.

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VAGINAL PROCESS AND SPERMATIC CORD

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• It encloses the vaginal cavity and is formed before the embryological descent of the testes .

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• The vaginal cavity communicates with the abdominal cavity through the vaginal opening located within the internal opening of the inguinal canal.

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POSITION OF THE SCROTUM �

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• The scrotum is located in:
• Inguinal region in the horse and the dog
• Below the inguinal region in ruminants
• Perineal in pigs
• Subanal in cats

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POSITION OF THE SCROTUM �

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• In ruminants the testes are carried with their long axes vertically; thus they possess a deep and pendulous scrotum.

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• The testes are orientated with their long axis horizontally in the horse and dog.
• While in the pig and cat, they are angled towards the anus.

BLOOD SUPPLY AND INNERVATION OF THE TESTIS AND ITS INVESTMENTS

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1-The testicular artery : branches directly from the abdominal aorta and passes along the abdominal wall.

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• suspended within the vascular plica together with the testicular vein.

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• Within the spermatic cord, the testicular artery is extremely convoluted.

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• The testicular artery extends branches to supply the epididymis and the original part of the deferent duct.

2-The testicular veins : form a very elaborate mesh-like plexus (plexus pampiniforrnis) around the arterial coils.

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• Arteriovenous anastomoses are present between the testicular artery and the surrounding veins within the spermatic cord .

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• The pampiniform plexus is ultimately reduced to a single vein (testicular vein), which drains in to the caudal vena cava.

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• The extensive contact between the vessels within the spermatic cord cools the blood within the artery on its descent to the testis.

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3-The testes receive nervous supply from the autonomic nervous system.

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• Parasympathetic fibers are derived from the vagal nerve and the pelvic plexus.

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• sympathetic fibers arise from the caudal mesenteric plexus and the pelvic plexus.

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The investments of the testis are vascularized by:

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1. the external pudendal artery and vein .

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• Lymphatics drain into the scrotal or superficial inguinal lymph nodes.

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• Nerve supply is provided by the ventral branches of the lumbar nerves.

- The iliohypogastric nerve

- the ilioinguinal nerve

- the genitofemoral nerve

�URETHRA

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• The male urethra extends from the internal urethral opening at the caudal end of the neck of the bladder to the external urethral opening at the free extremity of the penis.

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Based on its location it can be divided into :

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• Prostatic portion
• Pelvic portion
• Penile portion

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�ACCESSORY GENITAL GLANDS

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• The accessory genital glands are located along the pelvic portion of the urethra.

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• Their presence varies between the species and can include all or some of the following :
1. Ampullary gland.
2. Vesicular gland.
3. Prostate gland
4. Bulbourethral gland

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• The bull and stallion possess the full set of accessory glands.

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• The boar has vesicular, prostate and bulbourethral glands.

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• In the cat: the ampullary, prostate and the bulbourethral glands are present.

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• In the dog: only the ampullary and the prostate glands are present.

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�VESICULAR GLAND

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• The paired vesicular glands are present in all domestic mammals except the dog and the cat .

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• In ruminants and the horse, its excretory duct joins the deferent duct shortly before its termination, and this short, common passage is referred to as the ejaculatory duct.

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• The vesicular gland of the horse is a relatively large, hollow organ with a thick muscular wall and a smooth surface.

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• In the bull, this gland can be palpated transrectally.

PROSTATE GLAND

• The prostate is present in all domestic mammals .

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• In some it consists of two parts, one diffusely spread within the wall of the pelvic urethra(pars disseminata), the other a compact body (corpus prostatae) located external to the urethra.

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• The horse has only the compact part
• The small ruminants, only the disseminated part.

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• The bull has both parts, but the compact part is rather small and flat.
• In the dog and cat, the disseminated part is vestigial, but the compact part is large and globular.

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• Hypertrophy of the prostate gland is relatively common in older dogs and can lead to obstipation due to pressure from the enlarged prostate onto the rectum

�BULBOURETHRAL GLAND

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• The paired bulbourethral gland is found in all domestic mammals other than the dog.

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• It lies on the dorsal aspect of the pelvic urethra close to its pelvic exit.

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• It has the size of a walnut in the stallion and that of a cherry in the bull.

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• In the cat, it is very small and spherical.

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�PENIS

• Originates as Two crura from the ischial arch.

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• The crura converge to form the root of the penis, which continues as the body of the penis to the glans of the penis.

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• The penis is suspended between the thighs on the ventral surface of the trunk with its free extremity pointing towards the umbilicus in all domestic mammals except the cat, where it is directed caudally .

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• The organ is constructed of three columns of erectile tissue, which are independent at the root of the penis, but combined throughout the rest of the penis

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The penis is composed of the following divisions and subdivisions :

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1- root of the penis:

• crura of the penis (crura penis) formed by two columns of cavernous tissue (corpora cavernosa).

• unpaired bulb of the penis (bulbus penis) formed by the spongy body of the penis,

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2-body of the penis:

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• Cavernous body (corpus cavernosum)
• Spongy body (corpus spongiosum urethrae),

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3-glans of the penis:

• spongy body (corpus spongiosum glandis)
• Os penis, a modification of the cavernous body (dog).

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• The glans of the penis carries the external opening of the urethra in all domestic mammals

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• except in small ruminants, where a free urethral process prolongs the urethra beyond the glans penis

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There are two different types of penis :

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1-The fibroelastic type of penis :

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• ruminants and pigs

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• has small blood spaces divided by substantial amounts of tough fibroelastic tissue and is enclosed by a thick albugineous tunic surrounding both the cavernous body and the spongy body.

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• non-erect penis exhibits a sigmoid flexure between the thighs.

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• elongation of the penis is mainly achieved by straightening of the sigmoid flexure.

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• Relatively little additional blood is needed in order to make this type of penis become erect.

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2- Musculocavernous type of penis

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• the blood spaces are larger and the tunic and intervening septa more delicate and more muscular.

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• This musculocavernous type is found in the stallion and in carnivores.

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• A relatively larger volume of blood is required to achieve erection, which is marked by a significant increase in both diameter and length of the penis.

• In the dog, the distal end of the cavernous body is modified to form the penile bone (os penis) which is grooved ventrally to accommodate the urethra within the spongy body.

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�PREPUCE

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• is a fold of skin that covers the free end of the penis in the retracted state.

• It consists of an external lamina and an internal lamina, which are continuous at the preputial opening .

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• The equine prepuce is distinctive in having an additional fold that allows for considerable lengthening of the penis during erection.

• A paired muscle, which arises from the caudal vertebrae and descends through the perineum around the anus to reach the penis.
• In species with sigmoid flexure (ruminants and pig), it attaches to the caudal arch of this flexure.
• It is mainly composed of smooth muscle fibers.

The retractor of the penis:

BLOOD SUPPLY AND INNERVATION OF THE URETHRA AND THE PENIS

1-The internal pudendal artery supply :

• The urethra
• accessory genital glands
• the penis

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2-The artery of the bulb of the penis

• supplying the spongy body

the glans penis.

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3- The deep artery of the penis

• supplying the cavernous body

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4-The dorsal artery of the penis

• supply the glans penis.

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• Innervation of the penis is provided by the paired pudendal nerve, which conveys multiple parasympathetic fibers.

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• Numerous nerve endings are found in the glans penis and in the internal lamina of the prepuce.