Study on the development of the ovary and oocyte in Acrossocheilus fasciatus from Oujiang River

The histological features of the ovary and oocyte and breeding season of Acrossocheilus fasciatus of the Oujiang River were studied by biologic investigation and light-microscope.The results showed that the change of the oocytes of the female could be divided into five phases and the development of ovary could be devided into six stages,according to the morphological and histological features.In the ovaries at stage Ⅰ,the ovaries were transparent and linear structures.In the ovaries at stage Ⅱ,the oocytes were mostly at phase Ⅱ.In the ovaries at stage Ⅲ,the oocytes were mostly at phase Ⅲ,follicular membrane and yolk grain appeared in the cytoplast.There were few oocytes at phaseⅠand Ⅱin the ovaries at stage Ⅲ.In the ovaries at stage Ⅳ,the oocytes were mostly at phase Ⅳ.The nucleus was in excursion.The number of yolk grain increased.The ovaries were a cystoid structure.The oocytes appeared obviously by nude eyes.The ovaries at stage V were mature and the oocytes were dissociating.The ovaries at stage Ⅵ were in a recession,the ovaries were in relaxation and smaller in size.The breeding season of Acrossocheilus fasciatus of the Oujiang River was from May to August.The ovaries in reproductive season were mostly in stage Ⅳ from May to June.From July and August the ovaries were in stage Ⅲ or Ⅴ.The corresponding gonadosomatic index(GSI) of ovaries from May to August were 2.75%,8.54%,3.25% and 1.44% respectively.The results of this paper indicated that Acrossocheilus fasciatus of the Oujiang River belonged to consecutive spawning type.It can spawn many times during reproduction season.