Abstract
Extract: The developmental changes in the fractional nitrogen, protein, lipid, glycogen, and water content of major organs have been defined in the fetal rhesus monkey; the placenta, liver, brain, kidney, muscle, and lung were analyzed for each component at 50, 75, 100, 125, 150 and 175 days conceptual age, and the data were compared with those of healthy adult monkeys. Each organ was found to “mature” biochemically at characteristic rates. The relative water content of each organ showed a variable decrease with advancing fetal and postnatal life. The liver demonstrated the lowest value at each age studied, and the lung showed little change in its relative water content until structural maturation and extrauterine respiratory movements occurred. The value for fetal muscle showed the greatest rate of decrease with advancing gestation: the rate of change closely paralleled that previously reported for total body water during fetal life in this species.
The relative nitrogen and protein content of all organs except the liver increased sequentially during fetal life; lung showed a marked increase in these values during late gestation and was the only organ which did not show an additional increase between birth and adult life. Muscle showed the steepest rate of increase in relative protein content during fetal life. The value for liver decreased between 75 and 100 days gestational age; thereafter little change was apparent until after 150 days, when a marked increase occurred.
The relative lipid content of each fetal organ showed a characteristic pattern of change during fetal life; muscle and placenta demonstrated low values at all ages studied. The adult value for lung was reached by the time of full-term gestation. The relative lipid content of the liver was higher than those of other organs during the first half of pregnancy; little change occurred during fetal life, but major increases were seen between 150 and 175 days conceptual age, and between birth and adult life. The relative lipid content of the brain was greater than that of all other organs at the completion of fetal life; the level increased markedly during late gestation and continued after birth.
The relative glycogen content of the kidney and brain was low at all ages studied; the lung had elevated levels early in gestation which fell with structural maturity. The value for fetal muscle rose progressively until 150 days gestational age, then fell to adult levels. Adult values for liver were reached prior to the time of full-term gestation, but a marked decrese occurred during the neonatal period. These data will provide control values for studies into the nutritional factors influencing fetal growth and development.
Speculation: The patterns of physical, structural, biochemical, and behavioral development of the postnatal rhesus monkey are generally comparable to those of the postnatal human infant and child; enough data now exist to indicate that many of the processes of fetal biology of these two primate species are also similar. We suggest that investigations of agents which may be of benefit or detriment to the human fetus may be conducted during pregnancy in the rhesus monkey with some assurance that the resultant data may be relevant to events which occur during pregnancy in the human.
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Kerr, G., Campbell, J., Helmuth, A. et al. Growth and Development of the Fetal Rhesus Monkey (Macaca mulatta). II. Total Nitrogen, Protein, Lipid, Glycogen, and Water Composition of Major Organs. Pediatr Res 5, 151–158 (1971). https://doi.org/10.1203/00006450-197104000-00002
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DOI: https://doi.org/10.1203/00006450-197104000-00002