Fetal nutrition: supply, combustion, interconversion, and deposition
Faber, J.J.; Thornburg, K.L.
Federation Proceedings 45(10): 2502-2507
1986
ISSN/ISBN: 0014-9446 PMID: 3527758 Document Number: 282386
The study of placental transport is confounded by species differences, gestational differences and a permanent non-steady state. The histology of the interhaemal membrane, the degree of steric hindrance to diffusional exchange, the discrimination of electric charge, the flow pattern and the transfer of intact gamma -globulins are all species-specific. The creation of order based on the ultrastructure of the placental barrier is suggested. The gas diffusion capacity of the membrane changes during pregnancy. This change is initially due to an increase in placental mass, but the gas diffusion capacity continues to increase after placental growth has ceased, because of changes in surface area and thickness of the membrane. The non-steady state of foetal weight is accompanied by an uptake of nutrients far in excess of what is necessary to satisfy oxygen consumption. Estimations of venous and arterial cord blood chemistry are sufficient to distinguish the fraction of nutrient uptake that is dedicated to catabolism from the fraction that is dedicated to foetal growth.