Oocyte ultrastructure in bovine primordial to early tertiary follicles
Oocyte ultrastructure in bovine primordial to early tertiary follicles
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DOI：
10.1007/s004290050052
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发表时间：
1997-04-01
期刊：
影响因子：
--
通讯作者：
Boland, M
中科院分区：
文献类型：
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作者：
Fair, T;Hulshof, SCJ;Boland, M
本研究的目的是详细描述牛卵母细胞从原始卵泡开始生长到第三级卵泡发育完成过程中细胞质超微结构的变化。对原始卵泡、初级卵泡、次级卵泡和腔中早期卵泡的卵母细胞进行了光镜和电子显微镜分析。原始卵泡卵母细胞的特征是卵膜上有许多被覆的凹坑，核周围聚集着游离和细胞器相关的光滑(SER)和粗面(RER)内质网、圆形线粒体和高尔基复合体，位于略偏中心的位置。至次级卵泡期，卵母细胞微绒毛增多，线粒体拉长，高尔基复合体增多。次级卵泡期，卵母细胞与颗粒细胞之间的缝隙连接发育，卵母细胞内皮质颗粒形成，卵母细胞透明带形成，卵母细胞膜上被覆的凹坑减少。在直径达100微米的第三级卵泡卵母细胞中，高尔基复合体和脂滴数量增多，细胞器移位至皮质深层。在卵母细胞最终生长到120微米时，细胞器进一步移位到周边区，游离的SER和RER区的范围减小，单个皮质颗粒的数量增加，有帽的线粒体变得丰富，卵周隙发达。总之，牛卵母细胞的生长与许多细胞质细胞器的迁移和调节以及卵母细胞特有结构的发育有关，如透明带和皮质颗粒。
The aim of the present study was to describe in detail the changes occurring in the cytoplasmic ultrastructure of the bovine oocyte from the onset of growth in the primordial follicle until the completion of growth in the tertiary follicle. Bovine oocytes from primordial, primary, secondary and early to mid-antral follicles were processed and analysed by light and transmission electron microscopy. The primordial follicular oocyte was characterized by numerous coated pits on the oolemma and the accumulation of free and organelle-related smooth (SER) and rough (RER) endoplasmic reticulum, round mitochondria and Golgi complexes around the nucleus, which was located slightly off centre. Up to the secondary follicular stage the oocyte displayed an increase in the number of microvilli, elongated mitochondria and Golgi complexes. During the secondary follicular stage, formation of the zona pellucida, development of gap junctions between the oocyte and the granulosa cells, formation of the cortical granules in the oocyte and reduction in the number of coated pits on the oolemma were seen. In the tertiary follicular oocyte up to 100 mu m in diameter, the number of Golgi complexes and lipid droplets increased and the organelles were dislocated to the deep cortical region. During the final growth of the oocyte up to >120 mu m, the organelles were dislocated further to the peripheral region, the extent of the free SER and RER compartments were reduced, the number of individual cortical granules increased, hooded mitochondria became abundant and the perivitelline space developed. In conclusion, the growth of the bovine oocyte is associated with the relocation and modulation of a number of cytoplasmic organelles as well as the development of oocyte specific structures such as the zona pellucida and cortical granules.