Human Reproduction - Notes | Class 12 | Part 1: Male Reproductive System

Human Reproductive System: Male Reproductive System

• Reproduction is the production of young ones by an organism. Humans are sexually reproducing and viviparous.

1. Male Reproductive System

• It consists of paired testes, accessory ducts, accessory glands, and external genitalia (penis).

a. Paired Testes

• Primary sex organs that produce sperms and testosterone.
• Testes are formed within the abdomen. Soon after birth or at the 8^th month of pregnancy, they descend into the scrotal sac (scrotum) through the inguinal canal.
• The low temperature (2–2.5°C less than the body temperature) of the scrotum helps for proper functioning of testes and for spermatogenesis.
• Each testis is oval-shaped, with a length of 4–5 cm and a width of 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 germ 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

• Include rete testis, vasa efferentia, epididymis, and vas deferens. They conduct sperms from the testis as follows:
• Seminiferous tubules → rete testis (irregular cavities) → vasa efferentia (series of fine tubules) → epididymis (stores sperms temporarily) → vas deferens → joins with the duct of the seminal vesicle to form the ejaculatory duct → urethra → urethral meatus.
• Urethra receives ducts of the 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, calcium, 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 the uterus.
• Secretions of Cowper’s glands lubricate the penis.
• Secretions of the epididymis, vas deferens, seminal vesicle, and prostate help for maturation and motility of sperms.

d. Penis (External Genitalia)

• It is a copulatory organ made of erectile spongy tissue.
• When the spongy tissue is filled with blood, the penis erects. It facilitates insemination.
• The cone-shaped tip of the penis is called the glans penis. It is covered by the prepuce (foreskin).

Select Next Topic 👇

• Topic 2: Female Reproductive System
• Topic 3: Spermatogenesis
• Topic 4: Oogenesis
• Topic 5: Menstrual Cycle
• Topic 6: Fertilization and Implantation
• Topic 7: Pregnancy, Embryonic Development, Parturition, Lactation

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