Preimplantation diagnosis and embryo sexing offer great possibilities in the prevention of human diseases and in the field of animal production. These techniques involve blastomere isolation. Isolated blastomeres can grow in culture and develop as whole embryos. In this paper we describe, at the scanning electron microscope level, the characteristics of the plasma membrane surface of isolated blastomeres obtained from mouse embryos at the two-cell stage and of embryos grown to the 2/4- and 4/8-cell stages and compare them to control embryos grown in vitro. According to our results the in vitro manipulation of these embryos does not affect the surface characteristics of the plasma membrane in the early cleavage stages.