Fig. 9. Endothelial cell immunohistochemisty. Confocal images of mouse yolk sac vessels stained with PECAM-1 (A-E), VE-cadherin (F-J), and eNOS (K-O). A,F,K show large vessels from control yolk sacs; B,G,L are images of small vessels in controls. C,H,M are images of immunostaining in small, unremodeled vessels in low-hematocrit embryos, whereas D,I,N and E,J,O are images of large and small vessels, respectively, in low-hematocrit+hetastarch embryos. A noticeable reduction in eNOS staining was seen in low-hematocrit embryos, but both VE-cadherin and PECAM-1 staining persisted and remained localized to the plasma membrane. Elongated endothelial cell morphology in larger vessels is seen when viscous circulation is present, but unremodeled vessels had a more rounded morphology. Scale bar: 20 µm.