ANNUAL PATTERNS OF TESTICULAR DEVELOPMENT AND ACTIVITY IN THE CHINESEBULLFROG (RANA-RUGULOSA WIEGMANN)

Annual patterns of testicular development and of testicular and plasma androgen levels in the Chinese bullfrog, Rana rugulosa Wiegmann, are reported. The animals were collected from a frog culture farm from Nov ember of 1986 through November of 1987, at monthly intervals or more f requently during the breeding season. Proliferation of primary spermat ogonia was observed in November-December. In January-February, the num ber of primary spermatogonia decreased while secondary spermatogonia i ncreased. Primary and secondary spermatocytes showed little changes un til February when their number rose sharply. Although every stage of s permatogenesis was present year around, spermatozoa were massively for med in April-June. Thus, the spermatogenetic cycle of R. rugulosa, inh abiting subtropical Taiwan, is of continuous type. Leydig cells began to proliferate in late March and were abundant from April through July . Testicular androgen content showed basal values in January-February and August-December, began to increase in late March, peaked in April, and dropped markedly in May. The pattern of plasma androgen levels wa s similar to that of testicular androgen content, except peaking in mi ddle April-early May and dropped in late June. The unimodal pattern of seasonal changes in plasma androgen levels parallels Leydig cell prol iferation, spermatogenesis, testicular androgen content, and reproduct ive activities. In addition, the testicular weight was negatively corr elated with liver weight, but not with fat body weight during an annua l reproductive cycle of R. rugulosa.