Psychology 2040A/B Lecture Notes - Lecture 4: Prenatal Development, Blastocyst, Trophoblast
6 Jan 2019
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Prenatal development: occurs between conception and birth, takes appro. 266 days (9 months) for one celled zygote to develop into fetus ready to be born: prenatal development divided into 3 phases: period of the zygote, period of the embryo, period of the fetus. Period of the zygote: conception to implantation (14 days, fertilized ovum (zygote) divides by mitosis, cell di erentiation begins. Outer cells (trophoblast) become support structures: implantation: 10-14 days after conception blastocyst reaches uterus and attaches to wall of uterus and taps into mother"s blood supply. Some zygotes fail to survive this initial phase of prenatal development: fail to attach to uterine wall or attach to a bad site, genetically abnormal and fail to develop. Period of the embryo: 3rd through 8th week after conception, cell di erentiation. Ectoderm: nervous system, skin parts, sensory receptors. Mesoderm: muscles, bones, circulatory system, excretory system, reproductive system. Endoderm: digestive system, respiratory system: heart begins to beat (end of 4th week)
