Intercellular contacts in tumours of the vascular smooth muscle cells in man.

Electron microscopy has been used to study the cell to cell and cell to stroma contacts between smooth muscle cells (SMC) in normal vessels, angiomyolipoma and well and poorly differentiated vascular leiomyosarcoma. Micrographs were examined with a semiautomatic image analysis system. The length of the cell borders was calculated and the type and number of contacts per 100 micron cell perimeter and per 100 cells were determined. In all cases there was a predominance of simple appositions. Intermediate junctions, nexus junctions, interdigitations, intermediate contacts and junctional interdigitations were less frequently observed. In general, as the SMC become malignant and less differentiated the number of cell to stroma attachments decreases markedly and the intercellular contacts increase slightly.