Abstract
The neurological mutation weaver is characterized by defects in granule cell migration along Bergmann glial processes and by subsequent death and disposition of granule cells. Immunocytochemical localization of antisera raised against purified glial filament protein (AbGF) and transmission electron microscopy were used to visualize specific associations between granule neurons and astroglia in microcultures of cerebellar cells dissociated from normal (+/+), heterozygous (+/wv), and homozygous (wv/wv) B6CBA-w mouse cerebella. In microcultures of cells dissociated from normal B6CBA-Aw-J-wv (+/+) cerebella, staining with AbGF closely resembled results previously reported for cells taken from C57BL/6J (+/+) tissue. Two forms of stained astroglia were seen, one with a larger perikaryon and shorter processes, among which 12 to 20 unstained cells nestled; and another with a smaller cell soma and longer processes, along which a few unstained cells were seen. The first resembled astrocytes of the internal granular layer and white matter, the second Bergmann astroglia. In microcultures of heterozygous animals (+/wv), the number of granule cells was reduced slightly. Many stained astroglia resembled those from +/+ cerebella, but others had thickened processes and enlarged terminal “endfeet.” Granule cells associated with both forms of stained astroglia. Cultures from homozygous weaver (wv/wv) cerebella contained very few, if any, granule cells and did not exhibit specific neuronal/glial interactions characteristic of +/+ cells. Both forms of stained wv/wv glial cells had enlarged cell somata giving rise to stunted processes, suggesting that both Bergmann glia and astrocytes are affected by the weaver gene. By both immunocytochemical staining and electron microscopy, accumulation and tangling of glial filaments were seen. Immunocytochemical staining of weaver cerebellar tissue with AbGF also revealed abnormalities in astrocytes of the internal granular layer and white matter in addition to previously reported defects in Bergmann glia. Agglutination with five plant lectins, each with a different carbohydrate-binding specificity, revealed that postnatal weaver cerebellar cells agglutinate with the lectins concanavalin A and the wheat germ agglutinin, suggesting the persistence postnatally of embryonic cell surface elements on postnatal weaver cells.