Increased expression of VE-cadherin correlates temporally with differentiation of a restrictive endothelial barrier during normal angiogenesis in vivo

The purpose of this study was to evaluate temporal expression of VE- and N- cadherins within the angiogenic chick chorioallantoic membrane (CAM). Wheth er their relative patterns of expression changed in conjunction with abrupt differentiation of the restrictive CAM endothelial barrier between days 4. 5 and 5.0 of the 21 day gestation was evaluated. Immunoblots against VE-cad herin depicted an increase of VE-cadherin expression between days 4.5 and 5 .0, but no change in expression was detected between days 5.0 and 6.0. N-ca dherin expression, on the other hand, remained uniform from day 4.5 to day 6.0, Immunogold-labeled anti-VE-cadherin was found exclusively on the CAM e ndothelium, and principally along the lateral inter-endothelial junctions. Hence, VE-cadherin expression by the angiogenic endothelium was similar to that of adult endothelium. That VE-cadherin expression by the CAM endotheli um was increased between days 4.5 and 5.0 serves to suggest a temporal corr elation with the ontogeny of restrictive barrier function in angiogenic end othelium in vivo. (C) 1999 Harcourt Publishers Ltd.