Male reproductive system — A/L Biology

What must I remember about Male reproductive system?

• The male reproductive system consists of primary sex organs (paired testes) and accessory structures: epididymides, vas deferens, ejaculatory ducts, urethra, penis, and accessory glands (seminal vesicles, prostate, bulbourethral glands).
• Testes are housed outside the abdominal cavity in the scrotum to maintain a scrotal temperature ~2-3°C below core body temperature, required for viable spermatogenesis.
• Seminiferous tubules contain Sertoli cells (nourish developing sperm, form the blood-testis barrier, and secrete androgen-binding protein and inhibin) and spermatogenic germ cells undergoing spermatogenesis.
• Leydig cells (interstitial cells) located between seminiferous tubules synthesize and secrete testosterone in response to Luteinizing Hormone (LH / ICSH) from anterior pituitary.
• Accessory glands produce semen: Seminal vesicles contribute ~60% volume (alkaline, fructose for sperm ATP, prostaglandins, coagulating enzyme); Prostate contributes ~30% (milky, slightly acidic, citrate, PSA enzyme); Bulbourethral glands secrete alkaline mucus neutralizing residual urine.

Test yourself (1 minute)

1. Hormonal axis in males

   GnRH from hypothalamus stimulates anterior pituitary to secrete FSH (stimulates Sertoli cells for spermatogenesis) and LH (stimulates Leydig cells to produce Testosterone); Testosterone and Inhibin exert negative feedback on hypothalamus and pituitary.

2. Sperm ultrastructure

   Head contains haploid nucleus and Acrosome (hydrolytic enzymes like hyaluronidase for egg penetration); Midpiece packed with mitochondria for ATP generation; Tail (flagellum with 9+2 axoneme) for motility.

3. Spermatogenesis vs Spermiogenesis

   Spermatogenesis is the complete developmental sequence from spermatogonium to mature sperm; Spermiogenesis is the specific maturation phase converting non-motile spermatids into flagellated spermatozoa.

Practise Male reproductive system questions today

Source: NIE G.C.E. (A/L) Biology Syllabus & Resource Book, Unit 5

What should I study first?

What comes next?

Next in the syllabus

Where does Male reproductive system fit in the syllabus?

Year 2 · Term 1