Question

Describe briefly : Embryology of testicular descent.

Hint:

The descent of testes is a complex process influenced by genetic and hormonal factors, and any disruption during this phase can lead to conditions requiring early intervention.

Answer 1

Testicular descent is the process by which the testes move from the abdomen into the scrotum during fetal development. This process is crucial for normal male reproductive function, and failure of descent leads to conditions such as cryptorchidism (undescended testes).
Step 1: Embryological Development:
1. Initial Position: The testes begin their development in the abdomen near the kidneys, around 7 weeks of gestation.
2. Descent Process: The descent of the testes occurs in two phases: - Transabdominal Phase: The testes move from the abdomen to the inguinal region between 7 and 12 weeks, influenced by factors such as the Mullerian inhibiting substance and insulin-like hormone 3. - Inguinal Scrotal Phase: The testes then descend through the inguinal canal into the scrotum by 25 weeks, assisted by the growth of the gubernaculum, which guides the testes down.
Step 2: Factors Influencing Descent:
1. Hormonal Influence: The process is regulated by hormones, including androgens and insulin-like hormone 3, which stimulate the growth and contraction of the gubernaculum.
2. Genetic Factors: Mutations in genes responsible for normal testicular development, such as the INSL3 gene, can result in conditions like cryptorchidism.
Step 3: Clinical Implications:
1. Cryptorchidism: Failure of the testes to descend into the scrotum results in cryptorchidism, which requires medical or surgical intervention.
2. Timing: Normal testicular descent typically occurs by 9 months of gestation, and undescended testes should be corrected if not descended by 6 months after birth.