Fine structure of bovine morulae and blastocysts in vivo and in vitro
Fine structure of bovine morulae and blastocysts in vivo and in vitro
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DOI：
10.1007/s004290050249
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发表时间：
1999-06-01
期刊：
影响因子：
--
通讯作者：
Hoshi, H
中科院分区：
文献类型：
--
作者：
Abe, H;Otoi, T;Hoshi, H
用体外成熟和受精的卵母细胞在添加血清的培养基中发育的牛桑葚胚和囊胚的超微结构与非手术采集的超排卵牛桑葚胚和囊胚进行了比较。在体内来源的桑葚胚中，通过细胞质的电子密度和超微结构特征可以识别出两种特征细胞类型。一种呈浅色，细胞质电子密度低。这些细胞位于卵裂球簇的外周层，具有大量细胞器，如线粒体和高尔基体，并有微绒毛突出到卵裂周间隙。另一种细胞类型的细胞质染色比颜色较浅的细胞更密集。颜色较深的细胞通常比颜色较浅的细胞拥有较少的细胞器，但细胞质中存在许多溶酶体样结构。体外发育的桑葚胚也含有两种与体内桑葚胚相似的细胞。然而，大多数体外发育的细胞具有大量的脂滴，并且比体内来源的桑葚胚细胞含有更少的溶酶体样结构。在体内和体外实验中，囊胚明显分化为滋养细胞和内细胞团（ICM）细胞。在体内源性囊胚中，滋养层细胞的顶膜覆盖着大量的微绒毛，连接复合物发育良好，滋养层细胞和icm细胞的细胞质中存在脂滴，但并不丰富。在体外发育的囊胚中，滋养层细胞之间的连接复合物发育不全，滋养层细胞顶端微绒毛发育不全，含有大量的脂滴。这种脂滴的积聚在滋养层细胞中比在icm细胞中要高。体外发育胚胎的透明带较体内发育胚胎薄。本研究表明，体外发育和体内发育胚胎的超微结构特征存在显著差异，提示超微结构可能反映了以往研究中观察到的各种生理异常。
The ultrastructure of bovine morulae and blastocysts developed from in vitro-matured and -fertilized oocytes in a serum-supplemented medium was compared with that of morulae and blastocysts collected non-surgically from superovulated cows. In the in vivo-derived morulae, two characteristic cells types could be identified by the electron-density of their cytoplasm and by their ultrastructural features. One type appeared light in color with low electron-dense cytoplasm. These cells were located in the peripheral layer of the cluster of blastomeres, possessed numerous cellular organelles such as mitochondria and Golgi apparatus and had microvilli projecting into the perivitelline space. The other cell type was distinguished by cytoplasm that stained more densely than that of the lighter-appearing cells. The darker-appearing cells generally possessed fewer organelles than the lighter cells, but many lysosome-like structures were present in the cytoplasm. The in vitro-developed morulae also contained two types of cells similar to those observed in the in vivo morulae. However, most of the in vitro-developed cells possessed numerous lipid droplets and contained fewer lysosome-like structures than the cells of the in vivo-derived morulae. The blastocysts, both in vivo and in vitro, showed a clear differentiation of trophoblast cells and inner cell mass (ICM)-cells. In the in vivo-derived blastocyst, the apical membrane of trophoblast cells was covered with large, numerous microvilli and well-developed junctional complexes were observed, Lipid droplets were present in the cytoplasm of trophoblast and ICM-cells but were not abundant. In vitro-developed blastocysts showed less well-developed junctional complexes between trophoblast cells, less well-developed apical microvilli on the trophoblast cells, and contained large numbers of lipid droplets. This accumulation of lipid droplets was higher in the trophoblast cells than in the ICM-cells. The zonae pellucidae of in vitro-developed embryos were thinner than that of the in vivo-derived embryos. This study demonstrates conspicuous differences in the ultrastructural features between the in vivo-derived and in vitro-developed embryos, suggesting that the ultrastructure may reflect the various physiological anomalies observed in previous studies.