Morphological and histochemical observations on trophoblast and decidua of the basal plate of the human placenta at term

The trophoblastic cells of the basal plate at the end of pregnancy still have an important hormonal function, in contrast to the decidual cells which appear to exert their main function at the onset of pregnancy. Possibly the decidual cells are functionally replaced by the basal trophoblastic cells, which phagocytize and destroy them. Although both types of cells are structurally quite similar and appear to produce the same hormones, but at different times, genetically they are very different. They degenerate morphologically in much the same way, but the cause for the retrogressive change for each is distinct. The trophoblastic cells degenerate with reticulum‐fibrinoid inclusions which they have mainly phagocytized. The decidual cells perish with collagen inclusions formed from collagen fibers they in turn produced.