It consists of Paired testes, accessory ducts, accessory glands, and external genitalia.

Paired testes:

• Primary sex organs that produce sperms & testosterone.
• Testes are formed within the abdomen. Soon after the birth or at the 8th month of pregnancy they descend into the scrotal sac (scrotum) through inguinal canal.
• The low temperature (2-2.5°C less than the body temperature) of scrotum helps for proper functioning of testes and for spermatogenesis.
• Each testis is oval in shape. Length 4-5 cm, width: 2-3 cm.
• Each testis has about 250 testicular lobules. Each lobule contains 1-3 coiled seminiferous tubules.

• The seminiferous tubule is lined internally with spermatogenic cells (spermatogonia or male germ cells) & Sertoli cells (supporting cells).
• Sertoli cells give shape and nourishment to developing spermatogenic cells.
• The regions outside the seminiferous tubules (interstitial spaces) contain:
• 1. Small blood vessels.
• 2. Interstitial cells or Leydig cells. They secrete testicular hormones (androgens).
• 3. Immunologically competent cells.