Adult Testis Anatomy
To review, the human testis lies within the scrotum. The “sex cords” of the early embryo become follicles in the female ovary and seminiferous tubules in the male testes (Figs. 1.3, 1.4, and 1.5). The Sertoli cells in the seminiferous tubules are equivalent to the granulosa cells in the female follicle. The Leydig cells in the interstitium between the tubules are equivalent to the theca cells in the ovary. The testis structure is surprisingly similar to the ovary (Figs. 1.3, 1.4, and 1.5). The average testicular volume is 20 mL but varies. The right testis is usually 10% larger than the left. Normal longitudinal length of the testis is approximately 4.5–5.1 cm. The average weight of human testis is 15–19 g. The tunica albuginea of the testis in the male is exactly equivalent to the cortex of the ovary in the female, and in the female, it has “hitchhiked” the very important function of regulating primordial follicle suppression and recruitment. It is the densest and toughest connective tissue in the body. It is the denseness and toughness of this tunica albuginea that in the male protect the exposed testis but in the female control the rate of primordial follicle recruitment .