HISTOPATHOLOGIC APPROACHES TO CHEMICAL TOXICITY USING PRIMARY CULTURES OF DISSOCIATED NEURAL CELLS GROWN IN CHAMBER SLIDES

Morphologic lesions have received only limited attention as in vitro e ndpoints of toxicity. In the present work, ''tissue'' and cell morphol ogy of control and toxicant-treated primary dissociated cerebrocortica l cell cultures from fetal mice were examined using phase-contrast and bright-field microscopy. In untreated control cultures, a reproducibl e sequence of developmental events included cellular reaggregation, in tercolony bridging with cell migration, and neuronal apoptosis, with m aturation yielding confluent monolayers containing both neurons and gl ia. Because even mature cultures had regions of varying differentiatio n, an understanding of the normal developmental sequence was essential when assessing toxicant-treated cultures for damage. Chemicals induce d neuronotoxic, gliotoxic, and cytotoxic (i.e., nonspecific) patterns of morphologic damage in growing (< 6 day old) or mature (6-15 day old ) cultures in both a concentration-dependent and cell type-specific ma nner. In addition, exposure to some toxicants consistently reduced the staining intensity for glial fibrillary acidic protein in the astrocy te carpet prior to the appearance of structural damage. These data ind icate that histopathologic endpoints, including methods for neural-spe cific markers, represent potentially valuable criteria for in vitro as sessments of neurotoxicity.