Scanning electron microscopy of malignant gliomas. A comparative study of glioma cells in smear preparations and in tissue culture.

Smear preparations from 15 malignant gliomas, 2 metastatic carcinomas and from normal brain were examined by scanning electron microscopy. Tissue culture preparations from malignant gliomas were also studied. In the better differentiated areas of gliomas, the cells in smears were stellate with multiple long interweaving processes 0.25--1.3 micrometer in diameter which could be distinguished from myelinated nerve fibers (1.3--5 micrometer) and from fibrin (0.08--0.3 micrometer) by their thickness and arrangement in the tissue. The relationship of glial processes to blood vessels within the tumour was well demonstrated in smears. Metastatic carcinoma cells lacked the processes seen in glioma cell smears and did not show the same relationship to blood vessels. The more anaplastic glioma cells had fewer processes and ovoid cell bodies covered with surface ruffles and microvilli similar to the cell membrane projections in the nuclear regions of glioma cells in culture. The relationship of the surface morphology of glioma cells in smears to the known invasive nature of these tumours is discussed.