Abstract
In order to elucidate the surface uitrastructure in blastocysts recovered from the rabbit on Days 5 and 6 of pregnancy, this study was conducted by the use of scanning electron microscopy.
1. The blastocyst covering was lack of uniformity, and constituted with two thin layers.
2. The trophoblastic cells had a polygonal appearance although each cell varied in shape and size. Each of them was covered with slender microvilli.
3. The cells of inner cell mass made a group of cells as a disk. Each cell varied two types. The large cells were covered with some short microvilli, and the small cells had shorter one.
