Figure 5. Histopathology of the Placenta and Fetal Membranes.

Microscopic appearance of the chorionic plate (A) and fetal membranes (insert) from a saline control animal near term demonstrating intact amnion epithelium and collagen layer with absence of leukocytic infiltration; (B) Following 21 days of IAI, accumulation of neutrophils was observed marginating into the chorion (arrows), which represented the minimal criteria for histologic evidence of IAI. There was also a fetal vascular inflammatory response (arrow head); (C–D) Marked histologic evidence of infection was represented by both chorionic and amnionic layer involvement by neutrophils (arrows), defined as chorioamnionitis. The predominant effect of maternal antimicrobial therapy was to reduce the frequency and degree of the leukocytic inflammatory response in the amnionic layer (B vs. C). (H&E slides; mag. 400×, scale bar = 200µm; Amnion = a; Chorion = c, Decidua = d).