Human development begins with fertilization, the fusion of male and female gametes to form a single-celled . This initial phase, known as the germinal stage (Weeks 1–2), is characterized by rapid cell division called cleavage . As the zygote travels toward the uterus, it transforms into a morula and then a blastocyst , eventually implanting into the uterine wall. This critical "molecular conversation" between the embryo and the uterus is foundational for a successful pregnancy. The Blueprint of Complexity: The Embryonic Period
The (Weeks 3–8) is arguably the most dynamic period of development. It begins with gastrulation , a process where the embryo reorganizes into three distinct germ layers— ectoderm, mesoderm, and endoderm . These layers serve as the biological blueprint for all future structures: Download (01) embryologie humaine embryologie humaine pdf
Gives rise to the respiratory and digestive systems. Human development begins with fertilization, the fusion of