Development - o The blastocyst implants into the uterus...

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Development, Heredity, and Aging Prenatal development is an important part of an individual's life. About 7 of every 100 people are born with some type of birth defect. Prenatal Development Prenatal development is divided into the germinal, embryonic, and fetal periods. Developmental age is 14 days less than clinical age. Fertilization o Fertilization, the union of the oocyte and sperm cell, results in a zygote. Early Cell Division o The zygote undergoes divisions until it becomes an embryonic mass of cells. Blastocyst o The embryonic mass develops a cavity and is known as the blastocyst. o The blastocyst consists of a trophoblast and an inner cell mass, where the embryo forms. Implantation of the Blastocyst and Development of the Placenta
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Unformatted text preview: o The blastocyst implants into the uterus about 7 days after fertilization. o The embryonic portion of the placenta is derived from the trophoblast of the blastocyst. Formation of the Germ Layers o The embryo forms around the primitive streak, which forms about 14 days after fertilization. o All tissues of the body are derived from three primary germ layers: ectoderm, mesoderm, and endoderm. Neural Tube and Neural Crest Formation o The nervous system develops from a neural tube that forms in the ectodermal surface of the embryo and from neural crest cells derived from the developing neural tube....
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