Cytogenetical analysis of the germ cell in the domestic drake and mule drake.

Experiments were conducted to study the germ cell of testes in the domestic drake (Tsaiya drake) and the mule drake. The histological sections of testes of both drakes were compared in this study. The results showed that rapid testicular growth did not occur until 7 weeks of age in domestic drakes and 15 weeks of age in the mule drakes. The rate of growth of the testes and the increase in the ratio of testes weight to body weight in domestic drakes at different ages were much more rapid than in the mule drakes. However, the opposite results were found in the body weights. In the mule drakes, spermatogonia and primary spermatocytes could be observed in the seminiferous tubules, but no secondary spermatocytes, spermatids or spermatozoa in seminiferous tubules were found up to 52 weeks of age. This showed that the meiotic division had not occurred in the mule drakes. In the domestic drakes, spermatogonia in the seminiferous tubules were observed at 1 week of age. Primary spermatocytes of some males appeared as early as the third week of age. Secondary spermatocytes and spermatids in the seminiferous tubules of some drakes began to appear at 5 weeks of age as a result of the meiotic division of the spermatocytes. At 7 weeks of age, spermatids were in process of metamorphosis, and spermatozoa were first observed in the seminiferous tubules of the drake. All testes of drakes 9 weeks of age contained spermatozoa. The percentage of the seminiferous tubules containing spermatozoa increased gradually with age, and approached a plateau at 15 weeks of age.(ABSTRACT TRUNCATED AT 250 WORDS)