PSYB20H3 Lecture Notes - Gonadal Ridge, Semipermeable Membrane, Neural Tube
Document Summary
Learning outcomes: review the three stages of prenatal development and the key developmental milestones that occur during each stage, highlight the key developmental features of each month of pregnancy, discuss the role of the environment in development. Principles guiding development: development proceeds in a cephalocaudal (head to foot) direction, development proceeds from basic to more specialized characteristics/abilities, development proceeds in order of importance for survival. The inner layer becomes the embryo and the outer layer becomes a protective layer: only about half of fertilized ova are firmly implanted. Facial structures begin to form: second month, ears are formed, rudimentary skeleton, brains develop rapidly. In male embryo, production of testes begins once signalled by y chromosome. In female embryo, production of ovaries begins: fetal stage (9 weeks - birth): all major organ systems begin to function and the fetus grows rapidly, third month: fetus starts to move (cannot be felt) Fetus swallows, digests, and urinates: male fetuses secrete testosterone from testes.