CELL-CELL INTERACTIONS INFLUENCE SURVIVAL AND DIFFERENTIATION OF PURIFIED PURKINJE-CELLS IN-VITRO

To determine the role of cell-cell interactions in Purkinje cell survi val and dendritic differentiation, perinatal moose Purkinje cells were purified, and their development was analyzed in vitro. In isolation a t low density, Purkinje cell survival was poor, improved by neuronal c ontacts, either with purified granule neurons or with Purkinje cells t hemselves. Moreover, coculture with specific cell populations led to w idely different degrees of Purkinje cell differentiation. Purified Pur kinje cells cultured alone or with an inappropriate afferent, the mess y fibers, did not progress beyond immature forms. With astroglia, Purk inje cells had thin smooth processes. Proper Purkinje cell differentia tion was driven only by coculture with granule cells, resulting in den drites with spines receiving synapses. These results suggest that Purk inje cell differentiation is regulated by local epigenetic factors, pr ovided in large part by the granule neuron.