NATS 1675 Lecture Notes - Lecture 12: Pregnancy, Gestation, Organogenesis
4 Aug 2015
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Document Summary
Period of development before birth and is 38 weeks long counted from fertilization to birth (fetal age) If counted from last menstrual period it is 40 weeks +/- 2 weeks. Fetal age is a more accurate measurement, but is not commonly used clinically. Fetal age can be determined through ultrasound measurements. Babies are born +/- 2 weeks of their expected date. Third trimester is continued growth and preparation for life outside the woman"s. Period of gestation is divided into 2 termed trimesters : First trimester is the period of embryonic development and organogenesis. All organs are formed within the first 10 weeks of gestation. There is one exception to that the lungs; it begins gestation and goes into a holding stage. Size of her baby bump does not relate to the age of her fetus directly. Trophoblasts synonym for outer cell mass. Gastrulation a migration of blastocyst cells inward, leading to multiple distinct layers of tissue called germ layers.
