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What is Embryonic period of development is and explain in detail?
Development before bih is called prenatal development, and that after bih is called postnatal development. There are three stages in prenatal development. They are: 1. Preimplantation/pre-embryonic period 2. Embryonic period 3. Fetal period. Embryonic Period- It extends from 3rd week of intrauterine life to 8th week of intrauterine life. The following morphogenetic events take place during this period : 1. Trilaminar germ disc differentiation: Formation of three layered germ disc with the appearance of mesoderm in between ectoderm and endoderm. 2. Early organogenesis: Formation of primordia of various organs like lungs, hea, liver, etc. 3. Formation of extraembryonic suppoive organs and membranes: Placenta, umbilical cord, amnion, allantois. Ref:Inderbir Singh's Human Embryology, eleventh edition , pg. no.,2.