Male reproductive histology

Testis & Tubules - The Sperm Factory

• Tunica Albuginea: Dense white fibrous capsule deep to the visceral tunica vaginalis.
• Seminiferous Tubules: Site of spermatogenesis. Lined by germinal and Sertoli cells.
  • Sertoli Cells: "Nurse" cells. Form blood-testis barrier (tight junctions). Secrete Inhibin B, Androgen-Binding Protein (ABP). 📌 Sertoli Supports Sperm.
  • Spermatogenic Cells: Mature from basal spermatogonia to luminal spermatozoa.
• Interstitial Leydig Cells: Between tubules. Secrete testosterone (stimulated by LH). Contain eosinophilic Reinke crystals.

⭐ The Blood-Testis Barrier is crucial. It prevents an autoimmune attack on haploid spermatids, which are antigenically foreign as they appear after immune tolerance is established.

Genital Ducts - Sperm's Superhighway

• Pathway: Sperm maturation and transport follows a specific route.
  • 📌 Mnemonic: SEVEN UP (Seminiferous tubules, Epididymis, Vas Deferens, Ejaculatory Duct, Nothing, Urethra, Penis).

• Histological Highlights:
  • Epididymis: Pseudostratified columnar epithelium with long stereocilia (absorptive). Site of sperm maturation.
  • Ductus (Vas) Deferens: Thick tripartite muscularis layer (longitudinal, circular, longitudinal). Propels sperm via peristalsis.

⭐ Exam Favourite: The Ductus Deferens is identified by its thick, three-layered muscular wall, a feature crucial for its powerful contractile function during ejaculation.

Accessory Glands - Semen's Secret Sauce

• Seminal Vesicles (~70% of volume): Secrete an alkaline, viscous fluid.

  • Key products: Fructose (sperm energy source), prostaglandins (uterine contraction), fibrinogen (coagulation).
  • Histo: Pseudostratified columnar epithelium.

• Prostate Gland (~25% of volume): Secretes a milky, slightly acidic fluid.

  • Key products: Citrate (nutrient), enzymes like Prostate-Specific Antigen (PSA) which liquefies the coagulum.
  • Histo: Glands often contain corpora amylacea (laminated concretions) that increase with age.

• Bulbourethral (Cowper's) Glands (<1% of volume):

  • Secrete clear, thick mucus (pre-ejaculate) that lubricates the urethra and neutralizes residual acidic urine.

⭐ PSA is organ-specific but not cancer-specific. Levels can be elevated in Benign Prostatic Hyperplasia (BPH) and prostatitis, not just prostate cancer.

Penis & Urethra - The Delivery System

• Erectile Bodies:
  • • Corpora Cavernosa (x2): Paired dorsal cylinders; deep arteries dilate for erection.
  • • Corpus Spongiosum (x1): Ventral, contains urethra; prevents compression.
• Urethral Epithelium: Varies by region: transitional → pseudostratified/stratified columnar → stratified squamous (distally).

⭐ Buck's fascia, a deep fascial layer, encases all three erectile bodies. Its rupture leads to penile fracture.

High‑Yield Points - ⚡ Biggest Takeaways

• Sertoli cells form the blood-testis barrier, secrete inhibin B, and support spermatogenesis within seminiferous tubules.
• Leydig cells in the interstitium produce testosterone in response to LH.
• The epididymis has pseudostratified columnar epithelium with stereocilia for sperm maturation and fluid absorption.
• Seminal vesicles provide fructose-rich fluid, the largest volume contribution to semen.
• The prostate gland secretes PSA; corpora amylacea are common histological findings with age.
• The ductus deferens has a thick, three-layered muscular wall for powerful peristaltic ejaculation.