NATS 1675 Lecture Notes - Lecture 12: Gestation, Gastrulation, Pattern Formation
4 Aug 2015
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This is the 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. Nadel- french ohysician- looked at human development and recognized it was 40, 2 weeks from menstrual period. Babies are born more or less 2 weeks when they are supposed to be born. The period of gestation is divided into three equal periods termed trimesters : First trimester (3 months long) is the period of embryonic development and formation of organogenesis- formed in first 10 weeks of gestation; lung begins formation and then goes into holding pattern. Second trimester is a rapid period of growth-when pregnancy begins to show on woman"s body. Third trimester is continued growth and preparation for life outside the woman"s body -
