Search Results

On 10 days of pregnancy the blastocysts of 3 mm and 9 mm in diameters wereflushed out from the uterine horns of the Du-Chang-Ha and Dong-Bei-Min pigs.The blastocysts were divided into four parts,that is the embryonic disc,the animalpole,the lateral part and the vegetal pole.The outer and inner surface of the fourparts were observed with SEM and the findings are as follows:1,The 3 mm blastocystsThe outer surface of the embryonic disc was still covered with trophoblasticcells.Three kinds of cells can be discerned:the cell with round prominences andlong microvilli(MV);the cell with thin and long MV,the cell with smooth sur-face.The trophoblast cells in other areas of the blastocyst were similar but slightlyflat.The inner surface of the blactocyst consists of endoderm cells which weredifferent in the four parts.From the embryonic disc to the vegetal pole,the surfacestructure of the endoderm cells changed regularly from small to large from dome-shaped to flat and the distance between nuclei increased gradually.The MVs on thecell surface:became less.These findings suggested that endoderm cells weremoving from the center of the embryonic disc to the vegetal pole.There weremany holes on the marginal area of the cells.The edge of the cell on the innersurface of the vegetal pole forms a network.Many round granules can be seen inthe holes of the network.Their function may be for the transport of nutrients.2,The 9 mm blastocystsThe outer surface of the embryonic disc was not covered with trophobla-stic cells but covered with ectoderm cells.The ectoderm cells in the primitivestreak had long MV on their surface but short ones on other areas of the disc.The inner surface of the embryonic disc was endoderm cells.The MVs on theendoderm cells was much more numerous than the MVs on the ectoderm cells.Thedifferentiation of the cells in the pig blastocyst was also discussed.