Reproduction is the production of young ones by an organism. Humans are sexually reproducing and viviparous.
- It consists of paired testes, Accessory ducts, Accessory glands & external genitalia (penis).
a. 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 descent into the scrotal sac (scrotum) through inguinal canal.
- The low temperature (2-2.50 C less than the body temperature) of scrotum helps for proper functioning of testes and for spermatogenesis.
- Each testis is oval shaped. Length 4-5 cm, width: 2-3 cm.
- Each testis has about 250 testicular lobules.
- Each lobule contains 1-3 coiled seminiferous tubules.
- Seminiferous tubule is lined internally with
· Male germ cells (spermatogonia): They become sperms.
· Sertoli cells: They give nutrition to the germs cells.
- The regions outside the seminiferous tubules (interstitial spaces) contain small blood vessels, interstitial cells (Leydig cells) and immunologically competent cells.
- Leydig cells secrete testicular hormones (androgens).
b. Accessory ducts (Duct system)
- Include rete testis, vasa efferentia, epididymis & vas deferens. They conduct sperms from testis as follows:
- Seminiferous tubules → rete testis (irregular cavities) → vasa efferentia (series of fine tubules) → epididymis (stores sperms temporarily) → vas deferens → join with duct of seminal vesicle to form ejaculatory duct → urethra → urethral meatus.
- Urethra receives ducts of prostate and Cowper’s glands.
c. Accessory glands
- Include a prostate gland, a pair of seminal vesicles and a pair of Cowper’s glands (bulbo-urethral glands).
- Their collective secretion (seminal plasma) is rich in fructose, Ca and enzymes.
- Seminal plasma + sperms → semen.
- Functions of seminal plasma:
· Helps for transporting sperms.
· Supplies nutrients to sperms.
· Provides alkalinity to counteract the acidity of uterus.
· Secretions of Cowper’s glands lubricate the penis.
- Secretions of epididymis, vas deferens, seminal vesicle & prostate help for maturation and motility of sperms.
d. Penis (external genitalia)
- It is a copulatory organ made of erectile spongy tissue.
- When spongy tissue is filled with blood, the penis erects. It facilitates insemination.
- The cone-shaped tip of the penis is called glans penis. It is covered by prepuce (foreskin).