关键词: 中华大蟾蜍, 精巢, 繁殖, 生精小管, 睾丸间质细胞

Abstract: Objective　This study systematically compared the morphological index and histological structural characteristics of the testis in the Bufo gargarizan during and after reproduction phase, investigated the underlying patterns of change, and assessed its reproductive investment level and evolutionary position within reproductive biology.Methods　Morphological index such as body weight, testis weight, testis length and testis diameter was measured before and after breeding. The histological structure of the testis was revealed by paraffin-embedded sectioning and HE staining. The microstructure of the testis was photographed using Motic Images plus2.0 software and the diameter of the spermatogenic tubules was measured. SPSS 22.0 software was used to analyze the obtained morphological data before and after reproduction, and t test was used to analyze the significance of the difference in the above morphological index. Results　The result showed that there was no significant difference in the morphological indexes of body weight, testis weight, length of testis, diameter of testis and tubule diameter during and after reproduction phase. During the breeding period, the coefficient of testis was only 0.003 2±0.006, which was significantly smaller than that of the Rana spinosa with similar body size. After reproduction, the coefficient of testis decreased to 0.002 3±0.003, but the decreasing trend was slow. During the reproduction period, there were only 1-2 layers of spermatogonial stem cells in the wall of seminiferous tubules, and a large number of spermatozoa clustered in the lumen of seminiferous tubules. The process of spermatogonial stem cells in seminiferous tubules proliferating and differentiating into a large number of primary spermatocytes took about 1.5 months in Bufo gargarizans, which was faster than Feirana quadrana, Nanorana pleskei and Rana chensinensis in the north slope of the Qinling mountains. The interstitial tissue of testis was obviously visible in the period of reproduction. After reproduction, the interstitial tissue of testis was significantly reduced. The number and volume of Leydig’s cells were reduced too.Conclusion　The morphological index of the testis of Bufo gargarizans did not change significantly during and after reproduction. Low reproductive investment indicated that its reproductive evolution is relatively primitive. The histological structure of the testis changed obviously before and after reproduction. The process was similar to that of amphibians had reported, which suggested that the reproductive regulation mechanism of amphibians was similar. The differentiation rate of spermatogonial cells was related to the altitude, habitat and living habits of the species. The morphological and quantitative alterations in interstitial cells indirectly reflect fluctuations in androgen secretion levels and play a crucial regulatory role in spermatogenesis, the development of male sexual characteristics, and reproductive behaviors.

Key words: Bufo gargarizans, testis, reproduction, seminiferous tubules, Leydig cells