Survey of the intervillous space with villi (human placenta, full-term)

Stain: Perjodic Acid Schiff reaction (PAS). At the right and left side the chorionic plate (1) with few cross-sectioned umbilical vessels (2), at (3) a detached amnion. Cross-sections of thick stem villi (4) at the fetal side ramify into terminal villi (tertiary) that are found stuffed (due to fixation procedures) in the intervillous space. At several places fibrinoid accumulations of varying diameter (5) are seen as reddish-stained PAS-material associated with the villi