Changes in distribution of connective tissue components of human placentae with maturation.

The distributional changes of type IV collagen and laminin with normal maturation of human placentae were examined in relation to those of fibronectin by the histochemical methods including immunofluorescence staining. In the early chorionic villi, these components were detected along the trophoblastic basement membrane, around the fetal blood vessels, and in the villous stroma. Laminin was detected also in the pericellular matrices of nonvillous cytotrophoblasts where type IV collagen was rarely detected. In the late and term placentae, laminin and type IV collagen were detected along the trophoblastic basement membrane, while this structure was virtually not stained for fibronectin. These observations suggest that type IV collagen and laminin are the constituents of the trophoblastic basement membrane throughout the maturation period of the placentae, while fibronectin is a transient constituent.