The immunologic problem of pregnancy. II. Ultrastructure of isogeneic and allogeneic trophoblastic transplants

Fine structure of the placental labyrinth in the rat at term and during prolonged gestation

The fine structure of the placental labyrinth in the rat was described at term (Day 22) and during prolonged gestation (Day 23, 24 and 25). Gestation was prolonged by dialy subcutaneous injection of progesterone to the mothers from Day 20 through Day 24 of pregnancy. The placental labyrinth at term consisted of maternal and foetal blood spaces separated by three layers of trophoblast and an endothelium. During prolonged gestation (Day 24 and 25 only) the layers of trophoblast exhibited discontinuity, loss of cytoplasmic elements and the presence of fibronoid material. In addition ot the morphological observations, it was found that foetal blood glucose levels on Day 24 and 25 were significantly lower than values at term. The results were discussed in reference to placental insufficiency and its effect on the foetus.

Immunobiological function of the syncytiotrophoblast: a new theory

The main purpose of this paper is to present our hypothesis concerning the antigen-antibody complex formation and the resolution system inside the syncytiotrophoblast to explain immunologic fetomaternal relationships. This hypothesis, derived from the results of our experiments, might be an answer to why the fetus is not rejected by the mother, in contradistinction to other allografts. We also believe that this hypothesis makes important contributions to the explanation of the immunologic processes of cells, i.e., those processes which work against antigens inside a living body.