Abstract
Background:
Geese breeding holds economic importance, but their reproductive efficiency lags behind other poultry species, due to male fertility challenges including variation in semen quality, genetics, environmental, and management factors.

Aim:
The current study presents a comprehensive histological and histomorphometric analysis of adult geese testes, employing two anti-vimentin immunostaining markers to localize Sertoli cells and quantify their spatial distribution.

Methods:
Seven adult male geese (Anser anser domesticus) were used in this study. The birds euthanized and testes were collected, weighed and measured for the total length and width, then testes were preserved with Davidson’s solution for 24 hours, followed by histological sectioning and staining with Harris hematoxylin and eosin, other sections were prepared for immunostaining with rabbit and mouse anti-vimentin antibody markers, histomorphometric measurements included numbers and diameters of seminiferous tubules, thickness of tunica albuginea, number and diameter of Sertoli cells, and Sertoli cell index, the data were statistically analyzed to interpret differences between left and right testes.

Results:
Testes were paired and bean-shaped, with the left testis being significantly larger, heavier, and situated more cranially than the right. Microscopic analysis revealed that the tunica albuginea was thicker in the left testis. And the seminiferous tubules were densely packed, with a wider diameter and higher mitotic activity in the left testis compared to the right. Sertoli cells were more abundant in peripheral tubules compared with central tubules. Immunohistochemical analysis showed positive expression with rabbit polyclonal anti-vimentin antibody, with stronger staining in the left testis and higher cellular index, whereas the mouse monoclonal antibody exhibited no reactivity.

Conclusion:
Geese testes share some morphological and microscopic features with those of other avian species, and differ from mammal testes. These observations offer data for understanding reproductive physiology in geese, applications in the diagnosis of fertility-related diseases, and enhancing poultry farm management.

Key words: Geese; Immunohistochemical; Anti-vimentin; Sertoli cells; Testes.