凡纳滨对虾卵母细胞卵黄发生的超微结构

利用电镜研究凡纳滨对虾卵母细胞卵黄发生的全过程。结果表明 :凡纳滨对虾卵黄的发生是双源性的。卵黄发生早、中期是内源性卵黄大量合成的阶段 ,卵黄发生中、后期则以外源性卵黄的合成为主。内源性卵黄主要由内质网、线粒体、核糖体、溶酶体、高尔基器等多种胞器活跃参与形成。其中数量众多的囊泡状粗面内质网是形成内源性卵黄粒的最主要的细胞器 ;部分线粒体参与卵黄粒的合成并自身最终演变为卵黄粒 ;丰富的游离核糖体合成了大量致密的蛋白质颗粒并在卵质中直接聚集融合成无膜的卵黄粒 ;溶酶体通过吞噬、消化内含物来形成卵黄粒和脂滴 ,且方式多样 ;高尔基器不直接参与形成卵黄粒。外源性卵黄主要通过卵质膜的微吞饮活动从卵周隙或卵泡细胞中摄取外源物质来形成

Ultrastructure of vitellogenesis in the oocytes of Litopenaeus vannamei

The vitellogenesis of the oocytes in Litopenaeus vannamei was examined by electron microscopy.The results indicate a dual origin of the yolk.The active endogenous yolk formation occurred mainly in the primary and metaphase of vitellogenic oocytes.However, the active exogenous yolk formation played the most important role in the metaphase and anaphase of vitellogenic oocytes.The endoplasmic reticulum, mitochondrion, ribosome, lysosome and Golgi apparatus were all involved in the formation of endogenous yolk granules.Furthermore, large quantities of vesicular rough endoplasmic reticulum were the dominant organelles which took part in the endogenous yolk formation; some mitochondria participated in the endogenous yolk synthesizing and then developed into yolk granules directly; many free ribosomes synthesized numerous proteinous particles and formed yolk granules without membranes by aggregation and fusion of themselves; the lysosomes produced endogenous yolk granules by engulfing and digesting inclusions with various forms; the Golgi apparatus formed yolk granules indirectly.Exogenous yolk formation was carried out primarily by active microphagocytosis of the plasma membrane which uptook the exogenous materials from the perivitelline space or follicular cells.