Figure 1.

Expression of HtrA1 in first trimester of gestation. a) HtrA1 is expressed in the stroma of Mesenchymal Villous (MV) originated from Immature Intermediated Villous (IIM). The foetal vessel walls are positive for HtrA1 (arrows). b) High magnification of the MV boxed in a). Note the positive staining in the stroma around the foetal capillaries (erythrocytes are visible inside foetal capillaries). c) MV stained for HtrA1, note the strong immunostaining of the villous cytotrophoblast for HtrA1 (arrow). d) Cell islands. HtrA1 is strongly expressed in the stroma adjacent to the cell islands (arrows). e) the picture shows a cell column (CC) weakly stained for HtrA1 and a more evident immunostaining in the stroma adjacent to the CC showing the same staining depicted in fig. d) for cell islands. f) HtrA1 is strongly expressed in the fibrinoid deposits (FD) and in the foetal vessel walls. g) parallel section to that shown in e) showing FN immunostaining mainly present in the distal part of CC. h) parallel section to that shown in f) showing FN localized in the FD, in the villous stroma and in the foetal vessel walls. i) negative control for FN; l) negative control for HtrA1. Scale bars: a,d,e,f,g,h,i,l) 50 µm; b,c) 250 µm.