Correlation Between the Changes of Microstructure and Testosterone in Nuptial Pad of the Frog, Rana chensinensis

The nuptial pad microstructures of Rana chensinensis in the Qinling Mountain China were observed by light microscopy during the annual reproductive cycle; meanwhile, testosterone (T) and androgen receptor (AR) localization were examined by immunocytochemistry in the nuptial pad. The results indicated that the formation of nuptial spines was caused by multiplication of germinal cells, granular cells, and volume expansion of granular cells. The regression of nuptial spines was caused by desquamation of granular cell globules, which wrapped by a layer of horny cells and detaching from epidermis surface. The development of nuptial glands synchronized with nuptial spines morphogenesis. Secretory activity of the nuptial glands was active during courtship. The distribution of T and AR in germinal cells, granular cells and nuptial glands showed a good agreement with aspection of microstructures in nuptial pad. These indicated that the formation and regression of nuptial pad were regulated by T. Seasonal variation in the development of nuptial pad were associated with testis somatic index and spermatogenesis progress. It suggested that pad morphological characters reflected indirectly the development condition of testis.