Comparison of two types of endothelial cells in long term culture

Bovine aortic endothelial cells have been serially subcultured and maintained for ten months (24 passages) without any apparent loss of endothelial-like properties. There appear to be two endothelial cell types; one type is mononucleated, 40-60 mu in diameter, and the other (giant) cell type, multinucleate and 300-600 mu in diameter. Both cell types were identified as endothelial cells by established criteria; 1. ultrastructurally, by the presence of Weibel-Palade bodies, microfilaments and pinocytotic vesicles and 2. immunologically, by the presence of factor VIII antigen and thrombosthenin.