AJP - Cell Physiology, Vol 233, Issue 3 111-C124, Copyright © 1977 by American Physiological Society
Transfer of hydrophilic molecules by placenta and yolk sac of the guinea pig
K. L. Thornburg and J. J. Faber
Prenatal transfer of hydrophilic materials was studied in chronic guinea
pig preparations of ca. 30-65 days gestation. In most preparations the
vitelline (yolk sac placenta) circulation of one of the fetuses was ligated
between 1 and 20 days before the experiment. Fetal and maternal serum
protein concentrations were recorded as a function of the number of days
after ligation. Prenatal transfer of hydrophilic materials of 60-5,500
daltons molecular wt was consistent with diffusion, with some evidence of
steric restriction of the larger molecules. There was no difference between
operated and sham-operated or control fetuses. However, the transfer of
radiolabeled homologous gamma globulin ceased after ligation of the yolk
sac vessels. The transfer in control fetuses accounted for most of the
prenatal requirements of this protein, as calculated from the increases in
fetal weight and serum gamma globulin concentrations as a function of
gestational age. There was evidence of a nonspecific suppression of yolk
sac function by surgery but no evidence of fetal catabolism of gamma
globulin.
