Postnatal cerebellar cells of staggerer mutant mice express immature components on their surface

Abstract

THE histogenesis of the central nervous system is controlled, in part, by a defined sequence of cell-surface interactions^1,2. Cell-surface carbohydrates are prominent constituents of the external faces of plasma membranes^3–5 and are thought to be important to biological recognition^6,7. Recently, it has also been shown that some cell-surface carbohydrates change during the first 2 d after birth, an important period in development of the mouse cerebellum^8,9. Certain neurological mutations have been shown to express defects in positioning of particular cell types at various stages during cerebellar histogenesis^2,11–13. One of the most interesting of these is the staggerer (sg) mutant¹⁴. In this disorder granule cells degenerate after they have migrated into position in the granular layer. Before this expression of the disorder, the sites of synapse formation between the parallel fibre axons of granule cells and the dendrites of Purkinje cell neurones fail to form; in fact, even the tertiary branchlet spines, the potential postsynaptic sites, do not form^15–19. Even at birth, before obvious expression of the Purkinje cell defect, external granule cells of sg exhibit a reduced proliferative rate which results in a reduced number of external granule cells²⁰.