lI. hat' s Embryology ? Embryology is a kind of science which study the processes and the regulations of the development of human fetus 1. Preembryonic period: 1-2W 2. Embryonic period: 3-8W 3.Fetal period: 9-38WII.What’s Embryology? Embryology is a kind of science which study the processes and the regulations of the development of human fetus. 1.Preembryonic period: 1-2W 2.Embryonic period: 3-8W 3.Fetal period:9-38W