Morphometric ultrastructural analysis of mouse embryo during early development.
During preimplantation development of the mouse embryos a number of qualitative morphological changes is observed. The aim of the present paper was to perform the stereological analysis of some cytoplasmic structures which play an important role during development. The experiments were performed with embryos of Swiss mouse strain. Material for qualitative and quantitative evaluation at the ultrastructural level was prepared according to the method developed in our laboratory. Stereological investigations were performed after Weibel. The results were statistically elaborated. Volume fraction of the nucleoli, mitochondria and Golgi apparatus related to cytoplasm or total cells were evaluated. Additionally, the shape of the mitochondria was determined as a ratio long to short arm of this structure. Beginning with the 1-cell stage up to the morula the volume fraction of the nucleoli does not change. It is only in the blastocyst that a statistically significant increase in the fraction of these structures was noted both in the inner cell mass and in the trophoblast. After each cleavage of mouse embryos cell, mitochondria change their shape. They became round with transvere cristae in the morula stage and elongated in the blastocyst. Volume fraction of the mitochondria markedly increased after the 1sst and 4th embryos division. In the course of cleavage in the mouse a morphological evaluation of Golgi apparatus occurs from the form of swollen dictyosomes scattered in the whole cytoplasm in 1-cell embryos to the typical structure in the blastocyst. Volume fraction of the Golgi apparatus of the total cell is markedly decreased after the 1st cleavage division and up to the morula stage decreases slightly. In the blastocyst both in the inner cell mass and trophoblast Golgi apparatus markedly increases.
D000818:Animals; D002466:Cell Nucleolus; D002467:Cell Nucleus; D006063:Chorionic Gonadotropin / Q000494:pharmacology; D004622:Embryo, Mammalian / Q000648:ultrastructure*; D005260:Female; D006056:Golgi Apparatus; D051379:Mice; D008928:Mitochondria; D009865:Oocytes / Q000648:ultrastructure
D006063:Chorionic Gonadotropin