What major developmental events occur during blastogenesis?

In the context of human development and congenital disorders, blastogenesis refers to the first 28 days of prenatal development. It is a critical period characterized by the following major developmental events:1

• Establishment of the Body Plan: During this phase, the fundamental body plan of the organism is laid out.1
• Determination of Developmental Fate: The developmental fate of all parts of the embryo is determined, and specific domains of gene expression are established.1
• Early Cellular Differentiation: The process involves the transition from a zygote through cleavage to the formation of a blastocyst, which includes the segregation of the inner cell mass (destined to become the embryo) and the trophoblast (which contributes to the placenta).23

Because the early embryo is small and its developing structures are highly integrated and interdependent, disruptions during this stage are typically severe and often lethal, frequently resulting in malformations that affect multiple body systems. This contrasts with organogenesis, which occurs from day 29 to day 56 and generally involves more localized, less severe defects.14