| In this paper,the migaration of the primordial germ cells(PGCs),the formation of the genital ridges and the gonad differentiation of loach(Rana limnocharis)were studied by histological method,and the difference of the gonad differentiation under various temperature was also studied.The result showed that On day 1,the PGCs were in the dorsal peritoneal epithelium.The genital ridges were formed on day 4;The primordial gonads were formed on day 17;On day 22,the primordial gonads differentiated into ovaries or testes.The lots of tadpoles completed metamorphosis on day 45.Just from hatching to metamorphic,the tadpoles were cultivated in different water temperatures (18±1)℃,(23-25)℃,(30±1)℃,(32±1)℃,(34±1)℃.The sex ratio and percentage of male tadpoles were calculated after the experiment.The sex ratio of the control group (23-25)℃was approximately 1:1(1:1.06);at the temperature(18±1)℃,the sex ratio was 1.83:1,the percentage of male was 35.1%;at the temperature(30±1)℃,the sex ratio was 1:1.67,the percentage of male was 62.1%;at the temperature(32±1)℃,the sex ratio was 1:1.98,the percentage of male was 66.4%;at the temperature(34±1)℃,the sex ratio was 1:2.86,the percentage of male was 74.0%.The experiment showed that low temperature induced the tadpoles develop to female;high temperature induced the tadpoles develop to male.Just during the period of gonad differentiation,the Rana limnocharis PGCs,oogonia and spermatogonium could not be resoluted.To reseach the differentiation of they,I Observation their minor structure by electron microscope.Before gonad sex differentiation,there was no P450 aromatase activity in tadpole of both control and experimental groups.With the process of gonad sex differentiation,the activity of P450 aromatase increased.In control group(23-25)℃,P450 aromatase activity was higher than the experimental group(32±1)℃.In the tadpoles with completion of gonad differentiation,P450 aromatase activity in the ovaries was higher than that in the testes. |
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