Early Embryo Development

Abstract

The main events taking place during early embryo development are examined. Egg and sperm syngamy leads to the first mitotic spindle assembly and activates the following process that involve cleavage, compaction, and blastulation. The integrity of the first mitotic spindle is essential for a normal embryo development and cell commitment. Gastrulation is also described with the definition of the three germ layers and establishment of the body axis. It is postulated that each cell constituting an embryo is the target as well as the source of specific cues and retains a memory of its own proliferation history and positional changes along development. These complex interactions are regulated through differential gene expression and epigenetic restrictions that gradually limit cell potency to a more limited phenotype-related expression pattern.