Embryonic Development and Implantation

Embryonic development refers to the series of events that occur after fertilization leading to the formation of a multicellular embryo. Following fertilization, the zygote undergoes multiple rounds of mitotic cell divisions to generate a solid ball of cells known as the morula. The morula then undergoes compaction and forms a hollow sphere called the blastocyst, consisting of an inner cell mass and an outer layer of trophoblast cells. The inner cell mass will give rise to the embryo, while the trophoblast cells will be involved in implantation and placental formation.

Implantation is a crucial process in which the blastocyst attaches to the uterine wall and establishes vascular connections for nutrient exchange. The trophoblast cells undergo differentiation into cytotrophoblasts and syncytiotrophoblasts, which play essential roles in invading the endometrium and forming the placenta. The embryo then undergoes gastrulation, a process where the three primary germ layers (ectoderm, mesoderm, endoderm) form through a series of complex morphogenetic movements. These germ layers give rise to different tissues and organs, laying the foundation for the developing organism's body plan.