圆口铜鱼早期卵母细胞发生的超微结构

用透射电镜观察了圆口铜鱼早期卵母细胞超微结构,发现:第1时相,卵原细胞呈圆形,细胞核较大,核仁1个,由纤维中心、致密纤维组分、颗粒组分组成;核内异染色质少,常染色质多;细胞质中有1~2个核仁样体,线粒体数量少,其基质电子密度低,嵴不发达.第2时相,卵母细胞体积增大,核仁数目增多,形态上出现大小区别.早期细胞质中核仁样体增多,靠近核膜,不被线粒体包围;光面内质网较多,糖原颗粒均匀分布;线粒体出现聚集现象;中期线粒体包围核仁样体.晚期核仁样体由大变小,逐渐消失,细胞膜边缘开始形成胞质突起.第3时相,早期卵母细胞的细胞质形成大量突起,且越来越明显;中期放射带开始形成,滤泡细胞出现颗粒细胞和鞘膜细胞的分化,两种细胞的超微结构有显著差异;晚期卵母细胞周围胶原纤维发达,呈束状,鞘膜细胞扁平状,卵母细胞质中有丰富的细胞器.讨论了圆口铜鱼早期卵子发生的特点,并与铜鱼的卵子发生做了比较.

Ultrastructure of Early Oogenesis in Coreius Guichenoti

From Mar.2002 to Jun.2003,Coreius guichenoti was collected in Changjiang River and the structure of early oogenesis in Coreius guichenoti was observed by transmission electron microscope.The results are as follows: The ooganium is round,which has a big nucleolus.Its nucleolus is composed of fibrillar center,dense fibrillar component,and granular component.There are little heterochromatin and much euchromatin;the cytoplasm has 1 or 2 nucleolus like bodies;mitochondria are small in number,whose plasm has low density of electron and its cristae is not aboundant.In the phrase 2,oocyte increases in volume and nucleolus gets more.In the early period of this phrase,nucleolus like body increases in cytoplasm,which are close to nuclear membrane and not around by mitochondria.There are many smooth endoplasmic reticulum.Glycogen granules distribute even;mitochondria congregate together.In the late period,nucleolus like body becomes small and disappears with the formation of membrane protrude.As for phrase 3,the cytoplasm gradually protrudes in the early period;in the middle period,zone radiata begins to form;follicular cells differentiate into granulose cells and thecal cells.The two kinds of cells are different from each other in ultrastructure;in the later period,they are bunches of developed collagen fibrillar arround oocyte,the thecal cells are flat and there are many organelles in the oocyte.This paper discusses the following questions: the characters of Coreius guichenoti's ovarian development,and compares the oogenesis of Coreius guichenoti with that of Coreius heterodon.