. Human reproductive system The male reproductive system comprises of a pair of testes, accessory ducts, glands and external genitalia (Fig. . ) .
Testes are the primary male sex organs. They are a pair of ovoid bodies lying in the scrotum (Fig. . a) .
The scrotum is a sac of skin that hangs outside the abdominal cavity. Since viable sperms cannot be produced at normal body temperature, the scrotum is placed outside the abdominal cavity to provide a temperature - o C lower than the normal internal body temperature. Thus, the scrotum acts as a thermoregulator for spermatogenesis. Each testis is covered by an outermost fibrous tunica albuginea and is divided by septa into about - lobules each containing - highly coiled testicular tubules or seminiferous tubules.
These highly convoluted tubules which form percent of the testicular substance are the sites for sperm production. The stratified epithelium of the seminiferous tubule is made of two types of cells namely sertoli cells or nurse cells and spermatogonic cells or male germ cells. Sertoli cells are elongated and pyramidal and provide nourishment to the sperms till maturation. They also secrete inhibin , a hormone which is involved in the negative feedback control of sperm production.
Spermatogonic cells divide meiotically and differentiate to produce spermatozoa. Interstitial cells or Leydig cells are embedded in the soft connective tissue surrounding the seminiferous tubules. These cells are endocrine in nature and are Fig. .
Male reproductive system XII Std Biology-Zoology Chapter- XII Std Biology-Zoology Chapter- Human Reproduction characteristic features of the testes of mammals. It secretes androgens namely the testosterone hormone which initiates the process of spermatogenesis. Other immunologically competent cells are also present. The accessory ducts associated with the male reproductive system include rete testis, vasa efferentia, epididymis and vas deferens (Fig.
. b) . The seminiferous tubules of each lobule converge to form a tubulus rectus that conveys the sperms into the rete testis. The rete testis is a tubular network on the posterior side of the testis.
The sperms leave the