POLYPOID PROTRUSIONS OF CELL AND SYNCYTIUM SURFACES IN MATURE HUMAN PLACENTAS

In mature human placentas the free as well as the basal surface of the syncytium, the free surface of the endothelium of capillaries and stromal cells show polypoid cytoplasmic protrusions of 0,5-15 μ in diameter. They are found mainly in the basal and marginal zone of the placenta, lying closely related to fibrinoid deposits. The polypoid protrusions develop from broad evaginations. These evaginations enlarge, their base is transformed into a stalk, their cytoplasm becomes lighter, and the cell organelles decrease in number. After reaching a certain size, the protrusions are set free into the bloodstream or into the core of the villi. Histochemical reactions for enzymes and lipids are always, those for carbohydrates mostly negative. The Ninhydrin-Schiff-reaction gives a weak staining. - With respect to the significance of the protrusions it is interesting to note that they are found mainly in embryonic tissues and in highly active tissues which have an inadequate energy supply at the same time. © 1969 Springer-Verlag.