Male reproductive organs

Testis & Epididymis - The Sperm Factory

• Primary Functions: Spermatogenesis (sperm production) & Androgenesis (testosterone).
• Key Structures & Cells:
  • Seminiferous Tubules: Site of spermatogenesis.
    • Sertoli Cells: Support sperm development; form blood-testis barrier; secrete Inhibin B.
    • Leydig Cells: In interstitium; secrete testosterone in response to LH.
  • Epididymis: Site of sperm maturation and storage.

Sperm Pathway:

⭐ Clinical Pearl: The left testicular vein drains into the left renal vein, while the right testicular vein drains directly into the IVC. This anatomical difference explains the higher frequency of varicoceles on the left side.

Ductal System - The Transit Route

• Epididymis: Site of sperm maturation and storage (head, body, tail).
• Ductus (Vas) Deferens: Long muscular tube; travels in the spermatic cord, through the inguinal canal.
• Ejaculatory Duct: Union of ductus deferens & seminal vesicle duct; opens into prostatic urethra.

📌 Mnemonic: SEVEN UP (Seminiferous tubules, Epididymis, Vas deferens, Ejaculatory duct, Nothing, Urethra, Penis).

⭐ Vasectomy targets the Ductus (Vas) Deferens, typically within the superior part of the scrotum. This bilateral ligation prevents sperm from entering the ejaculatory duct, resulting in infertility.

Accessory Glands - The Fluid Crew

• Produce seminal fluid, which mixes with sperm from the epididymis to form semen. This fluid provides nutrients, a transport medium, and protection.

Penis & Neurovasculature - The Delivery System

• Structure: Composed of three erectile columns.
  • Corpora Cavernosa: Paired, dorsal columns responsible for erection.
  • Corpus Spongiosum: Single, ventral column containing the urethra; forms the glans.
• Neurovasculature:
  • Arterial Supply: Internal pudendal artery → Penile artery → Dorsal & Cavernosal (deep) arteries.
  • Venous Drainage: Deep dorsal vein.
  • Innervation (Autonomic): Parasympathetic fibers (pelvic splanchnic n., S2-S4) cause erection; sympathetics cause ejaculation.
  • Innervation (Somatic): Pudendal nerve provides sensation.

⭐ The dorsal nerve of the penis, the terminal branch of the pudendal nerve, supplies sensation to the glans. It is a key landmark for nerve blocks and is vulnerable in pelvic fractures.

📌 Point, Squeeze, Shoot: Parasympathetic (Erection), Sympathetic (Emission), Somatic (Ejaculation).

High‑Yield Points - ⚡ Biggest Takeaways

• Testicular artery from the aorta; left testicular vein drains to the left renal vein, right to the IVC.
• Testicular lymph drains to para-aortic nodes; scrotal lymph to superficial inguinal nodes.
• Prostate cancer typically arises in the peripheral zone; BPH in the transitional zone.
• Erection is parasympathetic (S2-S4); ejaculation is sympathetic (L1-L2).
• The pudendal nerve (S2-S4) provides key motor and sensory innervation to the perineum.
• The ductus deferens passes through the inguinal canal to form the ejaculatory duct.