Male reproductive system
The male reproductive system consists of a scrotum, a pair of testes, vasa efferentia, a pair of epididymis, a pair of vasa deferentia, a pair of ejaculatory ducts, a urethra, a penis and certain glands.
(i) Reproductive organ
(a) Scrotum: The scrotum is a pouch of pigmented skin arising from the lower abdominal wall and hanging between the legs. Its dermis contains almost a continuous layer of smooth muscle fibres called dartos tunic. The scrotum is divided internally into right and left scrotal sacs by a muscular partition, the septum scroti. A scar like raphae marks the position of the septum externally. The testes originate in the abdominal but latter, during the seventh month of development, descend permanently into the respective scrotal sac through passages termed inguinal canal. If an inguinal canal remains open or is torn, a loop of intestine may descent in the scrotum to produce the disorder of inguinal hernia.
- A spermatic cord connects testis with abdominal cavity. It consists of connective tissue that encloses an artery, a vein, a lymph vessel, a nerve, cremaster muscle and a vas deferens. A testis rests in it chamber over pad called gubernaculum.
- Descent of testes in scrotum provides a low temperature (of\[2C{}^\text{o}\]) for maintenance of spermatogenic tissue and formation of sperms. Failure of testes to descend in scrotum is cryptorchidism, the disorder that causes sterlity because sperm formation does not occur at the abdominal temperature.
- Men persistently wearing tight underpants or taking very hot baths may have a reduced sperm count almost leading to infertility.
- The scrotal sac of male homologous to female's labia major.
Variations in position of testes: In some mammals (lion, bull, horse), the testes remain permanently in the scrotum and keep functioning throughout the year as in man. In certain seasonally breeding mammals, such as bat, otter and llama, (Insectivora, Tubulidentata, chiroptera and most Rodentia) the testes enlarge, become functional, and descent into the scrotum in the breeding season, but thereafter ascent into the abdominal cavity, and become reduced and inactive. In a few cases (elephant, whale, seal) the testes remain permanently in the abdomen as the body temperature is low enough for sperm maturation. Scrotum is absent in such cases. Scrotum is in front of penis in Kangaroo.
(b) Testes: The testes are the primary sex organs. They are about 4 - 5 cm long, 2.5 cm wide and 3 cm thick. They are suspended in the scrotal sacs by spermatic cords.
(1) Protective coats (Tunicae): Each testis has three coverings - tunica vaginalis, tunica albuginea and tunica vasculosa. On one side each testis is covered by hollowed tunica vaginalis, a bilayer of peritoneum with a narrow coelomic cavity having coelomic fluid for sliding. The actual covering
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