Human Reproduction
Class 12 Biology (NCERT Core Lines) • NEET & Boards Quick Revision Notes
Humans are sexually reproducing and viviparous organisms. The reproductive events include
gametogenesis, insemination, fertilization, blastocyst formation & development, implantation,
gestation, and parturition.
1. The Male Reproductive System
Located in the pelvis region. It includes a pair of testes, accessory ducts, glands, and external
genitalia.
A. Testes (The Primary Sex Organs)
• Situated outside the abdominal cavity within a pouch called scrotum. The scrotum helps in
maintaining the low temperature of the testes (2–2.5°C lower than normal internal body
temperature) necessary for spermatogenesis.
• Each testis is oval, length 4 to 5 cm , width 2 to 3 cm . Covered by a dense covering.
• Each testis has about 250 compartments called testicular lobules .
• Each lobule contains 1 to 3 highly coiled seminiferous tubules where sperms are produced.
Seminiferous Tubule Cross-Section Linings:
• Male Germ Cells (Spermatogonia): Undergo meiotic divisions to form sperms.
• Sertoli Cells: Provide nutrition to the dividing germ cells.
• Leydig Cells (Interstitial Cells): Located in interstitial spaces outside tubules. They secrete
testicular hormones called androgens (Testosterone).
Class 12 Bio • Human Reproduction • NEET Revision Page 1
, Leydig Cells
Sertoli Cell
Spermatogonium Sperms
Fig 1.1: Simplified Schematic of Seminiferous Tubule (Cross Section)
B. Male Accessory Ducts & Glands
• Path of Sperm Transport: Seminiferous Tubules → Rete Testis → Vasa Efferentia →
Epididymis (stores sperm temporarily) → Vas Deferens → Ejaculatory Ducts → Urethra.
• Male Accessory Glands: Includes paired Seminal Vesicles , a Prostate gland , and paired
Bulbourethral glands (Cowper's) .
• Secretions constitute the seminal plasma which is rich in fructose, calcium, and certain
enzymes.
• Bulbourethral gland secretions also help in the lubrication of the penis .
NEET Booster Point:
Spermatozoa reach maturity and gain motility inside the Epididymis. Seminal plasma +
Sperms = Semen. Fructose acts as an energy source and is entirely absent in any other body
fluid.
2. The Female Reproductive System
Consists of a pair of ovaries, a pair of oviducts, uterus, cervix, vagina, and external genitalia, along
with a pair of mammary glands.
A. Ovaries (Primary Female Sex Organs)
• Produce the female gamete (ovum) and several steroid hormones (estrogen & progesterone).
• Located in lower abdomen; 2 to 4 cm in length. Connected to pelvic wall and uterus by
ligaments.
• Each ovary is covered by a thin epithelium enclosing the ovarian stroma, divided into
peripheral cortex and inner medulla.
Class 12 Bio • Human Reproduction • NEET Revision Page 2
Class 12 Biology (NCERT Core Lines) • NEET & Boards Quick Revision Notes
Humans are sexually reproducing and viviparous organisms. The reproductive events include
gametogenesis, insemination, fertilization, blastocyst formation & development, implantation,
gestation, and parturition.
1. The Male Reproductive System
Located in the pelvis region. It includes a pair of testes, accessory ducts, glands, and external
genitalia.
A. Testes (The Primary Sex Organs)
• Situated outside the abdominal cavity within a pouch called scrotum. The scrotum helps in
maintaining the low temperature of the testes (2–2.5°C lower than normal internal body
temperature) necessary for spermatogenesis.
• Each testis is oval, length 4 to 5 cm , width 2 to 3 cm . Covered by a dense covering.
• Each testis has about 250 compartments called testicular lobules .
• Each lobule contains 1 to 3 highly coiled seminiferous tubules where sperms are produced.
Seminiferous Tubule Cross-Section Linings:
• Male Germ Cells (Spermatogonia): Undergo meiotic divisions to form sperms.
• Sertoli Cells: Provide nutrition to the dividing germ cells.
• Leydig Cells (Interstitial Cells): Located in interstitial spaces outside tubules. They secrete
testicular hormones called androgens (Testosterone).
Class 12 Bio • Human Reproduction • NEET Revision Page 1
, Leydig Cells
Sertoli Cell
Spermatogonium Sperms
Fig 1.1: Simplified Schematic of Seminiferous Tubule (Cross Section)
B. Male Accessory Ducts & Glands
• Path of Sperm Transport: Seminiferous Tubules → Rete Testis → Vasa Efferentia →
Epididymis (stores sperm temporarily) → Vas Deferens → Ejaculatory Ducts → Urethra.
• Male Accessory Glands: Includes paired Seminal Vesicles , a Prostate gland , and paired
Bulbourethral glands (Cowper's) .
• Secretions constitute the seminal plasma which is rich in fructose, calcium, and certain
enzymes.
• Bulbourethral gland secretions also help in the lubrication of the penis .
NEET Booster Point:
Spermatozoa reach maturity and gain motility inside the Epididymis. Seminal plasma +
Sperms = Semen. Fructose acts as an energy source and is entirely absent in any other body
fluid.
2. The Female Reproductive System
Consists of a pair of ovaries, a pair of oviducts, uterus, cervix, vagina, and external genitalia, along
with a pair of mammary glands.
A. Ovaries (Primary Female Sex Organs)
• Produce the female gamete (ovum) and several steroid hormones (estrogen & progesterone).
• Located in lower abdomen; 2 to 4 cm in length. Connected to pelvic wall and uterus by
ligaments.
• Each ovary is covered by a thin epithelium enclosing the ovarian stroma, divided into
peripheral cortex and inner medulla.
Class 12 Bio • Human Reproduction • NEET Revision Page 2
