Interaction between glioma cells and normal brain tissue in organ culture studied by scanning electron microscopy.

Scanning electron microscopy was employed to investigate cocultures between normal rat brain fragments and spheroids consisting of rat glioma cells. Lamellipodia were seen to arise from tumor cells at the border between the two structures and touch the surface of the fragment. Cytoplasmic extensions from malignant cells appeared to penetrate into the brain fragment. Leading lamellae were extended from the tumor cells as they migrated along the normal surface and gradually covered the fragment. Tumor cells formed broad foot-plates against the normal surface. No alterations of the brain fragment were observed ahead of the tumor cells. Thus there were specific changes of the surface microarchitecture of the malignant cells, but not of the normal brain tissue.