PSYC 2450 Lecture Notes - Lecture 4: Embryonic Disc, Semipermeable Membrane, Amnion
Document Summary
Germinal period from conception to implantation and lasts 14 days. Period of the embryo this is where all vital organs are formed and lasts from week 3 to week 8. Period of the fetus this where growth and refinement of the fetus occurs and lasts from week 9 to birth: germinal period. The embryonic disk develops into the embryo. The outer layer transforms into the following: Amnion: is a cushion against blows, helps regulate temperature. Chorion: surrounds the amnion and the lining develops into the placenta. Placenta: is a semi-permeable membrane used for the exchange of oxygen and nutrients between baby and mother; blood cannot pass. Through; the placenta is fully formed by 4 months of age: embryonic period. The formation of vital organs occurs during this period. During week 3, cell differentiation occurs as following . Ectoderm: forms into the nervous system, skin, and hair. Mesoderm: forms into muscle, bones, and circulatory system.