Time sequence of PECAM-1 movement on human umbilical vein tissue during PMN transmigration.

A PMN (stained with FM 1-43, located within the framed area) was transmigrating through the endothelium of human umbilical vein tissue that was previously immunostained with PECAM-1 antibody (Alexa Fluor 488). For picture clarity, only Alexa Fluor 488 images are displayed here. Different panels showed the depth-combined confocal images of PECAM-1 obtained at different times as indicated. PECAM-1 molecules around the transmigration site moved away from one another to leave an opening at 1 minute and almost resealed at 2 minutes. By the end of this PMN transmigration process the interendothelial boundary restored almost to the original state.