Abstract: [Objective] The aim of the present study was to characterize the activity and proliferation of spermatogonial stem cells （SSCs） from testes of Boer goats at different months of age during in vitro culture. [Method] Testes of Boer goats at 1, 3, 5 and 58 months of age were sampled, and the development of them was observed by histological method. The testicular tissues from goats at different months of age were separated to single cell by three-step enzyme digestion method. The total number of digestive cells and the number of dead cells was observed by trypan blue staining. The SSCs were purified with differential adhesion method and cultured for 10 days. The number of Thy-1⁺ cells in suspension before purification, after purification and cultured for 10 days was determined by flow cytometry. After cultured for 10 days, the SSCs clones were identified by alkaline phosphatase staining, and the number and area of clones formed by SSCs from testes of goats at different months of age were statistically measured. [Result] Testicular histological observation demonstrated that goats aged 1 month had the least number of germ cells in lumen of contorted seminiferous tubule, germ cells of all levels gradually developed with the increase of months of age, while seminiferous epithelium of goats aged 58 months was evidently degraded. After three-step enzyme digestion, the highest total number of testicular cells obtained before and after purification was observed in goats aged 5 months, which was significantly （P<0.05） higher than that in goats aged 1 month. There was no significant （P>0.05） difference in survival rate of testicular cells before and after purification for goats at different months of age. Among pre- and post-purification testicular cells and purified SSCs cultured for 10 days, the highest proportion of Thy-1⁺ cells in the total number of testicular cells was found in goats aged 1 month, which was significantly （P<0.05） higher than that in goats aged the other months. After 10 days of culture, the SSCs clones from testes of goats at different months of age were positive for alkaline phosphatase. The average number of SSCs formed clones from testes of goats aged 1 month was significantly （P<0.05） higher than that of goats aged the other months, while no significant （P>0.05） difference in average area of SSCs formed clones among goats at different months of age was observed. [Conclusion] Boer goats aged 5 months had the highest total number of cells in testes. Those aged 1 month had the lowest total number of cells in testes, while had the highest activity and proliferation efficiency of SSCs.

Key words: Boer goat, testis, spermatogonial stem cell, activity, proliferation, flow cytometry