Male Reproductive System and Spermatogenesis Notes

Embryology, anatomy, and physiology of the male reproductive system

• Testes origin and descent

  • Begin development in the abdominal cavity.

  • Attached to a tissue called the gubernaculum (cord-like connection).

  • The gubernaculum stretches and pulls the testes down through a canal in the groin area: the inguinal canal.

  • As they descend, testes wrap a piece of peritoneum around them to form tunica vaginalis.

  • Objective (from lecture): know where testes start and how tunica vaginalis is formed.

  • Summary: testes descend from abdomen to scrotum via gubernaculum through the inguinal canal; tunica vaginalis forms from peritoneum surrounding the testes.

• Cryptorchidism (undescended testis) and inguinal canal passage

  • In some babies, the testis remains in or near the inguinal canal; reasons include testis larger than canal or obstruction.

  • Possible positions: behind the inguinal canal, mid-canal, or above the canal.

  • Easy fix: testosterone shot to encourage descent; if unsuccessful, surgical orchiopexy (~20 minutes) to descend the testis.

  • Consequence of non-descent: higher testicular temperature impairs spermatogenesis, increasing risk of infertility.

  • Visual: anatomy shows testis passing through the inguinal canal on the path to the scrotum.

• Inguinal hernia and abdominal wall integrity

  • Sometimes the region around the inguinal canal weakens, allowing the bowel to herniate through the canal.

  • Clinical note: hernias can cause pain and fragility of the abdominal wall; treatment involves surgical repair with sutures and mesh as needed.

  • The spermatic cord is in this region; descent and canal pathology relate to both hernias and fertility considerations.

• Anatomy of the spermatic cord and supporting structures

  • The cord passes through the inguinal canal and contains:

  • Blood vessels: testicular artery and pampiniform plexus.

  • Nerves: genitofemoral nerve/plexus.

  • Duct: ductus (vas) deferens.

  • Lymphatics.

  • Coverings: cremaster muscle and surrounding fascia envelop the cord and testis.

  • Function: the cord connects the testis to the abdomen and provides pathway for vessels, nerves, and ducts.

• Heat exchange and temperature regulation for the testes

  • The pampiniform plexus cools arterial blood entering the testis; the testes stay around 2 °F cooler than core body temperature (≈ 1.1 °C cooler).

  • Mechanism helps maintain an environment conducive to spermatogenesis.

  • If the temperature rises, cremaster and other tunics relax or contract to move the testes closer or further from the body to regulate cooling.

  • Quantitatively: $$ ext{Temperature difference} \