Gross Placental Morphology and Pregnancy Outcome in Macaca nemestrina
Various measures have been suggested to estimate placental functional efficiency. Gruenwald and Minh (1961) used placental weight as one index of placental function in humans. They found that variation in placental weight is not significant and concluded that fetal size is not determined by the placenta in normal pregnancy. Placental weight is a poor predictor of birth weight (Gruenwald and Mihn, 1961; Thomson, Billewicz, and Hytten, 1969). Thomson et al. (1969), reviewing the relation between placental weight and birth weight in normal and abnormal pregnancies, concluded that placental insufficiency due to small size is rare. Fetal-placental weight ratios may correlate with placental efficiency. Lubchenco (1976) indicated that this measure is based on the assumption that the growth-retarded fetus is limited by small placental size and may have a greater fetal-placental weight ratio. Another functional measure, probably correlated with placental weight, is trophoblastic surface or mean villous area (Aherne and Dunnill, 1966). During gestation the trophoblastic surface increases and the membrane becomes thinner, suggesting greater placental efficiency near term. In a study of the relation between placental insufficiency and the small-for-date baby, Scott and Jordan (1972) incorporated general placental appearance, cord and membrane characteristics, abnormalities, histologic assessment, and weight into a scoring system. The weighted scores discriminated somewhat between cases of placental insufficiency and controls. The present study describes the gross morphology of 59 pigtail macaque (Macaca nemestrina) placentas and, in a smaller sample of term-gestation placentas, examines the relation between placental characteristics and pregnancy outcome.
KeywordsBirth Weight Pregnancy Outcome Breech Presentation Placental Weight Membrane Insertion
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