Uptake of Protein in Swallowed Amniotic Fluid by Monkey Fetal Intestine in Utero

The monkey fetal intestine has the capacity to take up macromolecular protein contained within swallowed amniotic fluid, and it may prove feasible to introduce compounds beneficial to the developing human fetus via the amniosis fluid.

Abstract

Horseradish peroxidase, a macromolecular protein of mol wt ~40,000 was injected into the amniotic sac of 4 pregnant monkeys.Seven hours later, segments of fetal small intestine were fixed, sectioned, and incubated for peroxidase in a diaminobenzidine-hydrogen peroxide medium.Light and electron microscopic examination revealed peroxidase uptake in 3 animals, 2 of which represented term fetuses and 1 a middle trimester fetus.Absorbed peroxidase granules were most abundant in cells lining the upper regions of the villi and were found throughout the cytoplasm of the apical half of the cells.Frozen sections incubated for both acid phosphatase and peroxidase revealed a superimposed reaction for both enzymes in the cell apex, suggesting that at least part of the incorporated peroxidase is degraded by lysosomes.Thus, the monkey fetal intestine has the capacity to take up macromolecular protein contained within swallowed amniotic fluid.It may prove feasible to introduce compounds beneficial to the developing human fetus via the amniotic fluid.It has been well established that the human fetal intestine from the 4th month onwards exhibits a high degree of morphological and biochemical maturity, 1 -3 and that under in vitro conditions it possesses the capacity to absorb glucose, 4 and, possibly, amino acids 5 against a concentration gradient.Its ability to actually function in vivo, however, has not yet been demonstrated.Although transmission of serum proteins and antibodies from pregnant