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Download Lecture 20 Pregnancy and Fetal Development Placental Functions
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Placental Functions Exchange Lecture 20 Pregnancy and Fetal Development Endocrine Placenta John J. Parrish Chemical Protection Placental Functions Exchange Physical Protection Similarities in Early Development Endocrine •Gas •Transient •Nutrients •Waste products •Estrogen Placenta •Progesterone •HCG •eCG •PL Chemical Protection Physical Protection •Immunosupression MAN •Shock Absorber PIG BIRD •Prevents infiltration by maternal defenses •Filters toxins Developmental Features Germ layers 13-14 Open neural tube Fusion of chorioamniontic folds Ewe Sow Woman 14 10-14 7-8 10-14 20 15-21 13 18 17 16 Heart beat apparent 24 21-22 20 16 25 Limb buds visible Cotelydons first appear 24 25 30 28-35 17-18 28 Eye differentiation 40 30-45 42-49 21-28 Birth 340 280 147-155 112 50 3 40 2 30 20 266 10 Critical Organ Systems Develop Early! Ovulation 0 1 Weight (kg) Cow Parturition Mare Length (cm) Developmental Horizons Fetal Development in the Human 0 0 4 8 12 16 20 24 28 32 36 40 Age of Fetus (weeks since last menstruation) 1 Rump Crown Factors Influencing Fetal Growth Genetics Environment Fetal Hormones Species Mother Nutrition Size, Parity Thyroid Placenta Blood flow Size Growth hormone Breed Litter size Estimates of Age • Crown rump length Genotype Insulin • Length femur, radius or tibia • Circumference of head Factors Influencing Fetal Growth Factors Influencing Fetal Growth Genetics Genetics Species Species Breed Breed Litter size Litter size Genotype Genotype Factors Influencing Fetal Growth Factors Influencing Fetal Growth Genetics Genetics Species Species Breed Breed Litter size Litter size Genotype Genotype Certains lines of animals may grow faster. 2 Factors Influencing Fetal Growth Factors Influencing Fetal Growth Environment Environment Mother Nutrition Size, Parity Mother Nutrition Size, Parity Placenta Blood flow Size Placenta Blood flow Size Factors Influencing Fetal Growth Uterine Size Changes During Pregnancy Hyperplasia » Increase in # of cells Fetal Hormones Skeletal and muscular development Hypertrophy » Increase in size of cells Thyroid Increased energy substrate availability and stimulates placental growth Stimulates fetal growth Insulin Stretching Growth hormone Umbilical Vein Ductus Venosus Liver Portal Vein Vena Cava Foramen Ovale Left Atrium Head and Heart Lungs Relative P4 and E2 Placenta Right Atrium Aorta Tissues Umbilical Arteries Ductus Arteriosus Weeks of Gestation Ovulation 3 Relative P4 and E2 Relative P4 and E2 Weeks of Gestation Relative P4 and E2 Ovulation Ovulation Weeks of Gestation 4 Progesterone Maintains Pregnancy! Progesterone is Essential To Maintain Pregnancy Corpus Luteum Placenta Species Gestation Length Placental Takeover Sow Cow Ewe Mare Human 3.8 mo 9 mo 5 mo 11 mo 9 mo 3.8 mo(none) 6 - 8 mo 50 d 70 d 60-70 d Other Species in Which Placenta Does not Take-over Progesterone Production Bitch Queen Alpaca, Llama, Camel Rabbit Goat 5
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