Male genital organs.

Involved in the development, maturation, transport and deposition of the male gametes (spermatozoa).
It consists of the paired testes,
the convoluted duct of the epididymis (ductus epididymidis),
the deferent duct (ductus deferens), the urethra (pars pelvina urethra) and the accessory glands

1. Male genital organs G M Lochi

2. Male Reproductive system Involved in the development, maturation, transport and deposition of the male gametes (spermatozoa). It consists of the paired testes, the convoluted duct of the epididymis (ductus epididymidis ), the deferent duct (ductus deferens), the urethra (pars pelvina urethra) and the accessory glands

3. The Testes The testes produce both sperm and hormones . The epididymis, stores spermatozoa during maturation before they pass to the deferent duct and the urethra. The accessory glands also drain into the urethra and contribute to the volume of semen. The distal part of the urethra forms the combined path for the passage of both urine and semen.

4. Testis (orchis} The testis , or male gonads (Greek orchis, Latin testis) , are paired organs, which take their embryological origin from the gonadal primordium on the medial of aspect of the mesonephros in the lumbar region, in a similar manner to the ovaries in females.

5. Structure of the testis The surface of the tes t is is invested by a dense fibrous capsule 1-2mm thick ( albugineous tunic, tunica albuginea) Composed of collagenous fibres and contains larger blood vessels These are visible on the surface of the testes in a pattern, characteristic of each species. The visceral vaginal tunic is a serous membrane continuous with the peritoneum that covers the fibrous capsule and gives a smooth appearance to the surface of the testis .

6. Hormones of testes Testosterone is a sex hormone that plays important roles in the body. In men, it's thought to  regulate sex drive (libido) , bone mass, fat distribution, muscle mass and strength, and the production of red blood cells and sperm.

7. Testes Fibrous capsule ( albugineous tunic, tunica albuginea), • Septa (septula testis), • Mediastinum (mediastinum testis). Contorted serniniferous tubules • Straight serniniferous tubules ( tubuli serniniferi recti), • Spaces within the mediastinum (testicular network, rete testis) and • Efferent ducts (ductuli efferentes ).

8. Each testicular lobule includes between two and five contorted tubules, which are the site of spermatogenesis. The wall of these tubules contains spermatogenic cells and sustentacular (Sertoli - )cells, which have supporting and hormone- producing properties. They are responsible for the regulation of spermatogenesis, supplying the nutrients to spermatogenic cells during the different stages of development and the release of spermatozoa into the lumen of the tubule

9. Each contorted seminiferous tubule is looped, so that it opens with both ends into a network of confluent spaces within the mediastinum, called the rete testis bules straighten out to become the straight seminiferous tubules ( tubuli seminiferi recti). The interstitial tissue filling the space between the tubules contains Leydig-cells, which are the principal producers of the androgenic steroidal hormones, such as testosterone . Each rete testes is drained by eight to twelve convoluted efferent ducts that perforate the fibrous capsule to enter into the head of the epididyrnis

10. Epididymis The epididyrnis is firmly attached along the testis and consists of the coils of the elongated convoluted tubules , which are held together by connective tissue. It can be divided into three parts Head (caput epididyrnidis ), • Body (corpus epididyrnidis ), • Tail (cauda epididyrnidis ).

11. scrotum , which are especially well developed in the stallion and the boar. The duct of the epididyrnis emerges at its tail and continues as the ductus deferens. In the duct of the epididymis, spermatozoa mature, tes ticular fluid is absorbed, cell fragments undergo phagocytosis and nutrients for the spermatozoa are secreted. Spermatozoa are stored in the tail of the epididyrnis until ejaculation . Length of the epididymal duct in the domestic species:

12. Deferent duct The deferent duct is the direct continuation of the duct of the epididymis. It originates as the undulating part of the tail of the epididymis and gradually straightens as it passes along the medial border of the testis. It ascends within the spermatic cord and enters the abdominal cavity through the inguinal canal.

13. Blood supply, lymphatic drainage and innervation of the testis The testicular artery (a . testicularis ) branches directly from the . abdominal aorta and passes along the abdominal wall, suspended within the vascular plica together with the testicular vein. The testicular veins form a very elaborate mesh-like plexus

14. Urethra The male urethra extends from the internal urethral opening ( ostium urethrae intemum ) a t the caudal end of the neck of the bladder to the external urethral opening (ostium urethrae extemum ) at the free extremity of the penis. Based on its location it can be divided into a pelvic portion (pars pelvina ) and a penile portion (pars penina ).

15. Accessory genital glands

16. Vesicular glands (seminal vesicles)  – These glands are typically paired and are composed of simple columnar glandular epithelium which is arranged in lobules. The excretory ducts are lined by stratified columnar epithelium. Vesicular glands are absent in carnivores but present in horses, swine and ruminants.

17. Prostate gland The prostate glands consists of the main body and a disseminate portion. The body is surrounded by a thick collagenous capsule while the disseminate portion is embedded in loose collagenous matrix extending along the dorsal aspect of the urethra and eventually extends laterally and ventrally to join the body. The gland is histologically composed of tubuloalveolar structures composed of low columnar to cuboidal cells, have apocrine gland type secretory activity and have acidophilic granules and lipid droplets in the epithelial cytoplasm. The body is well developed in carnivores and horses while the disseminate portion is better developed in cattle and swine. Rams do not have a well developed prostate.

18. Bulbourethral gland These are paired structures located dorsolaterally to the pelvic urethra and are composed of paired tubuloalveolar glands with columnar epithelium. The ducts of this gland are lined by columnar, pseudostratified or transitional epithelium. All domestic animals except for dogs have bulbourethral glands. The mucus production from this gland has lubricating function and clears the urethra of urine.