The main organ of the reproductive system is the testis. There are two hanging scrotums or scrotums at the thigh joint. The left scrotum is larger and the right smaller. The testicles are located inside the scrotum. Each testicle is oval and partially flattened. Its length is 2 inches and weight is 10-12 grams.
Each testicle is covered by 3 integuments. Tunica vaginalis, tunica albuginea and tunica vasculosa testis. The outer layer is the tunica vaginalis, the middle layer is the tunica albuginea and the inner layer is the tunica vasculosa.
Each testicle divides into 250 cells or segments. Each segment contains 1-4 patchy seminiferous tubules. Each testicle contains about 1000 seminiferous tubules. A seminiferous tubule is about 500 mm long.
Many seminiferous tubules join together to form a straight duct. The straight ducts join to form the reti testis. The reti testes join together to form the vas deferens or vasa efferentia.
Function of Testis
(i) Produces sperm.
(ii) Secretes the hormone testosterone.