Colocalization of P-selectin and CD41 on platelets adhering to endovascular trophoblasts and cultured EVTs. Sections of placental tissue at 10 weeks of gestation were double stained with rhodamine (red) and FITC (green). Panels B-D are the sequential sections of panel A and higher magnifications of the boxed area indicated in the sequential section of panel A. P-selectin (B; red) was colocalized with CD-41 (C; green) on platelets that adhered to endovascular trophoblasts (A; green). After 24-hour culture of isolated EVTs with platelets, EVTs were detached from the dishes and were double stained. (F,H,L) Phase-contrast images. (E-F) CD41 (green) and CD146/MCAM (red). (G-H) CD62P/P-selectin (green) and CD146/MCAM (red). (I-L) CD62P/P-selectin (green) and CD41 (red). CD41⁺ platelets were adhered to CD146⁺ EVTs (E-F). Most of these platelets expressed P-selectin on the cell surface, showing that they had been activated (G-L). Bars show 20 μm. Original magnification × 400 (A), × 800 (panels B-D), and × 1200 (panels E-L).