The Testis
The testes are paired male gonads responsible for spermatogenesis and the production of androgenic hormones (primarily testosterone).
Microscopic Organization
| Structure/Cell | Function |
|---|---|
| Seminiferous Tubules | Sites of spermatogenesis. |
| Sertoli Cells | Support spermatogenesis, form the blood-testis barrier, secrete Inhibin B. |
| Leydig Cells | Found in the interstitium; secrete testosterone in response to LH. |
Key Physiology
- Blood-Testis Barrier: Established by tight junctions between adjacent Sertoli cells; protects developing sperm from the immune system.
- Regulation: LH stimulates Leydig cells to produce testosterone; FSH stimulates Sertoli cells to support sperm development and produce androgen-binding protein (ABP).
High-Yield Exam Pearl:
Testicular tumors are categorized as germ cell or non-germ cell. Leydig cell tumors are non-germ cell tumors often associated with Reinke crystals (pathognomonic) and can cause gynecomastia due to increased estrogen production (via peripheral aromatization of excess testosterone).