Intercellular junctional specializations in human basal cell carcinoma. A freeze-fracture study

Intercellular junctions of various types were found on the membrane fracture faces of human nodular basal cell carcinoma (BCC) cells. The junctional types represented include desmosomes, tight junctions, and gap junctions. A semiquantitative comparison of undifferentiated and differentiated nodular BCC showed that gap and tight junctions were observed on all exposed membrane fracture interfaces of the differentiated tumors, while only fifty six per cent of the membrane interfaces of the undifferentiated tumor exhibited similar junctional specializations. These membrane specializations may be a partial reflection of differentiation among the different types of BCC and their contribution to the less invasive character of nodular BCC cannot be ruled out.