Ciliation of bovine aortic endothelial cells in culture.

Solitary cilia were observed by electron microscopy in senescent bovine aortic endothelial cells in culture. Such single cilia have previously been seen in several tissues of various species, but as far as we know they have not been identified in cultured endothelial cells. The analysis of ultrathin sections enabled us to show that the cilia originated in one of the two centrioles. Vacuolar structures located at one end of the centrioles were also observed and might occur during the lengthening of the cilium. Moreover, the surface replication technique allowed us to show that the cilia could extend out of the cell. As senescent endothelial cells enter a quiescent stage, they could build up such a cilium as was observed for some strains of cultured fibroblasts.