Cell surface changes during preimplantation development in the mouse

Scanning electron microscopy reveals microvilli on all preimplantation stages, indicates that their number and length may be dependent on embryo size, and provides examples of regional alterations in their number. Cellular adherence, as evidence by interactions of microvilli, migration of cellular processes, and junctional complexes, increases during development and is accompanied by changes in the shapes of cells and embryos. Cell surfaces bordering the blastocoel differ markedly from the outer cell surfaces of the embryo.