the early stage of embroyonic development during which rapid mitotic cell

The first two weeks of development, the preembryonic stage, is a period of cell division and differentiation. The events of this stage include fertilization, transportation of the zygote through the uterine tube, mitotic cell divisions (cleavage), formation of embryonic tissue and extraembryonic membranes (amnion, chorion, allantois, placenta, and umbilical cord), and the beginning of implantation of the blastocyst into the uterine wall. The term conceptus refers to all the products of conception including all structures that develop from the fertilized ovum (zygote), including the embryo and its extraembryonic membranes.