Identification of challenged subarachnoid free cells.

Three distinct types of free cell contours are recognizable in scanning electron microscopy (SEM) on the leptomeningeal sheaths of dogs twelve days after an intrathecal injection of bacillus of dogs twelve days after an intrathecal injection of bacillus Calmette-Guerin (BCG). Macrophages posses abundant plasmalemnal blebs which are shown in transmission electron microscopy (TEM) to be composed of large membrane-bound vacuoles. Smooth surfaced lymphoblasts exhibit many basal microvilli that rest upon and often indent the plasmalemma of an underlying pial cell. Neutrophils display many microvilli over their rounded, chrysanthemum-like surfaces. The consistency with which these external features are expressed suggests that each cell type possesses characteristic surface topography, at least under these conditions of challenge.