Intermediate size filaments and microfilaments in frog mesenteric capillaries.

Intermediate size filaments of mesenchymal origin in endothelial cells as well as tonofilaments could be identified by immunofluorescence. Both types of filaments form bundles which run in parallel to the main capillary axis. Filamentous actin could also be detected by this technique. The immunofluorescence of f-actin forms patch-like arrays irregularly distributed along the capillary and striated arrays which are oriented in some cases in parallel to the main capillary axis.