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Fertilization and Development. So that’s what happens after! . Fertilization. DAY 0 When sperm penetrates egg Sperm releases special enzymes to do this Forms a ZYGOTE – FERTILIZATION OCCURS Recombination occurs: Combining of genetic info from both parents Occurs in Fallopian tube.
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Fertilization and Development So that’s what happens after!
Fertilization • DAY 0 • When sperm penetrates egg • Sperm releases special enzymes to do this • Forms a ZYGOTE – FERTILIZATION OCCURS • Recombination occurs: • Combining of genetic info from both parents • Occurs in Fallopian tube
Early Development- The First Week • Zygote begins to divide, divide, divide • UNDERGOING MITOSIS!!!!!!! • Hopping along the Fallopian Tube trail! • Implantation of zygote in uterus • Occurs around day 7
Early Development- Gastrulation • Cells in zygote form into 3 distinct layers • Endoderm: • Digestive and other inner organs • Mesoderm: • Circulatory • Ectoderm: • Nervous • Skin • The cells within each layer will DIFFERENTIATE – MITOSIS!!!! • Become different (skin cells, heart cells, etc.)
The Role of the Placenta • Develops at 3 weeks • Placenta is a fetal organ • Connects mother and fetus • PLACE OF: • RESPIRATION (GAS EXCHANGE) • NOURISHMENT (GETTING NUTRIENTS) • EXCRETION (RID OF WASTES)
First and Second Trimester Dangers!!!! • Critical Development stage • Drugs, alcohol, and medicines can severely damage embryo/fetus • This can halt development or cause major developmental issues • Not taking care can result in miscarriage or severe deformities of child
Later Development • 8 weeks = FETUS • Umbilical cord fully formed at 3 months (12 weeks) • Body systems become more specialized • Fetus becomes bigger • Total human gestation period = about 40 weeks (“full term” at 37 weeks)
Cool Website! • http://www.ehd.org/movies-index.php