PSY 2105 Chapter Notes - Chapter 4: Prenatal Development, Fetus, Egg Cell
23 Nov 2016
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Prenatal development begins at conception or fertilization. When a sperm unites with ovum to form a single cell it is called zygote. Zygote receives 23 chromosomes from mother and 23 from father. The period of the zygote (conception to second week) Multiples rapidity travels 10 cm in 4 days from fallopian tube to uterous. Implantation takes about a week, zygote settles into blood enriches lining of uterus. The period of the zygote ends about two weeks after fertilization when the female usually misses her first period, by this time the women may suspect she is pregnant. Embryo: developing organism from the third week, when implantation is complete, through he eighth week after conception. First only the size of an apple seed, all major internal and external structures form during this period. During the embryonic period three major structures develop. Amniotic sac: fluid containing watertight membrane that surrounds and protects the embryo or fetus.
