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Chapter-08 Fetus, Placenta and Membranes

BOOK TITLE: Essentials of Obstetrics

Author
1. Kumar Pratap
2. Thomas Anita
ISBN
9788180613623
DOI
10.5005/jp/books/10288_8
Edition
1/e
Publishing Year
2004
Pages
8
Author Affiliations
1. Kasturba Hospital, Manipal, Karnataka, India, Manipal Assisted Reproductive Centre (MARC); Kasturba Medical College, Manipal Academy of Higher Education, Manipal, Karnataka, India, Kasturba Medical College, Manipal Assisted Reproductive Center (MARC), Manipal Academy of Higher Education (MAHE), Manipal, Karnataka, India, Kasturba Medical College, Manipal Academy of Higher Education, Manipal, Karnataka, India, Kasturba Medical College, Manipal Assisted Reproductive Centre (MARC), Manipal Academy of Higher Education (MAHE), Manipal, Karnataka, India, Manipal Assisted Reproductive Centre (MARC); Kasturba Medical College, Manipal Academy of Higher Education (MAHE), Mangalore, Karnataka, India, Karnataka, Manipal, Kasturba Medical College, Manipal, Karnataka, India, Manipal, Karnataka, India, Kasturba Medical College and Hospital, Manipal University, Manipal, Karnataka, India, Kasturba Medical College, Manipal University, Manipal, India, Kasturba Medical College, Manipal University, Manipal, Karnataka, India, Kast
2. Kasturba Medical College, Manipal, India, Kasturba Medical College, Manipal, Karnataka, India
Chapter keywords
human placenta, villous hemochorial structure, fetal allograft, ovum, fallopian tube, uterine cavity, morula, pellucid, blastocyst, cytotrophoblasts, peripheral syncitiotrophoblasts, deciduas, myometrium, multinucleated giant cells, placental septa, basal plate, intervillous spaces, placenta, central fluid filled cavity, primary trophoblastic cell mass, inner cell mass, embryo, nitrogenous wastes, urea, creatinine, uric acid, functioning kidney, amino acids, maternal plasma, lipids, pregnancy, fatty acids, lung secretions, phospholipids, lecithin, cholesterol, estrogens, progesterone, insulin levels, diabetic pregnancies, lung fluid, air sacs, pharynx, trachea, amniotic fluid, breathing movements, oligohydramnios, lung hypoplasia, canalicular period

Abstract

The human placenta is a villous hemochorial structure, which plays a critical role in maternal fetal transfer, has a complex synthetic capacity and plays a role in the immunological acceptance of the fetal allograft. The ovum is fertilised in the fallopian tube and enters the uterine cavity as a morula which rapidly sheds its surrounding zone pellucida and converts itself into a blastocyst. During the early weeks of gestation the cytotrophoblasts penetrate the peripheral syncitiotrophoblasts and spread into the underlying decidua even up to the myometrium where they fuse to form typical multinucleated giant cells the function of which is unknown. The placental septa appear during the third month protruding into the intervillous spaces from the basal plate and divides the placenta into 15 to 20 lobes. The placental septa appear during the third month protruding into the intervillous spaces from the basal plate and divides the placenta into 15 to 20 lobes. The morula becomes a blastocyst by formation of a central fluid filled cavity. This separates the primary trophoblastic cell mass from the inner cell mass which forms the embryo. Nitrogenous wastes are present like urea, creatinine and uric acid from the functioning kidney. Amino acids are in the same concentration as maternal plasma. Lipids increase as pregnancy progresses, half of which is in the form of fatty acids. Lung secretions contribute phospholipids, lecithin and cholesterol. Estrogens and progesterone with their metabolites are also found. Insulin levels increase toward term and are higher in diabetic pregnancies. Lung fluid is essential for development by ‘splinting’ the air sacs. This enters the pharynx through the trachea and is swallowed. Amniotic fluid is important for development probably by providing unrestricted breathing movements. Oligohydramnios can result in lung hypoplasia particularly when it occurs early in gestation at the canalicular period.

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