Trimester Specific Anatomical and Histological Characterization of Testicular Descent and Development in Sheep Foetuses.

BACKGROUND: This study aimed to investigate the morphological, histological and ultrastructural characteristics of prenatal testicular development in male Hamdani crossbred sheep foetuses. METHODS: A total of 17 male foetuses with gestational ages ranging from 50 to 125 days were examined. Gestational age was estimated using crown-Rectum length (CRL) measurements and the foetuses were classified according to trimester. Macroscopic evaluations were performed to determine the position of the testes in relation to the abdominal cavity, inguinal canal and scrotum. Testicular length, width and weight were measured and statistically analysed. Histological examinations were conducted on paraffin sections stained with Crossmon's trichrome, while ultrastructural features were evaluated using scanning electron microscopy (SEM). RESULTS: Testicular descent was observed to begin around Day 50 of gestation and progressed toward the inguinal canal; however, complete descent into the scrotum had not occurred by Day 125. Morphometric measurements showed a significant increase in testicular size and weight with advancing gestational age. Histological findings revealed the progressive formation and organization of seminiferous tubules, the presence of Sertoli and Leydig cells, and the development of interstitial tissue. SEM observations provided detailed visualization of the surface architecture and cellular organization of the developing foetal testes. CONCLUSION: This study provides a comprehensive developmental timeline of testicular organogenesis in Hamdani crossbred sheep foetuses. The findings contribute to the understanding of foetal reproductive biology and offer valuable anatomical data for comparative developmental studies and the evaluation of congenital testicular disorders.