Astrocytic Cell Clones from Mouse Cerebella Induce Differentiation of Embryonic Neuroblasts

Abstract

Two roles have been proposed for astroglia in establishing the cellular architecture of the developing mammalian cerebellum. First, radially oriented astroglial processes are thought to guide the migration of immature granule cells from the pial surface (ventricular zone), where they undergo their final mitosis to the internal granular layer where they form synaptic connections (Rakic 1971). Second, after neuronal migration, protoplasmic astrocytes organize mature granule cells into compartments (Palay and Chan-Palay 1974). The aim of the present work was to search for a role of astroglial cells in differentiation of the neuroblasts of the cerebellum. This requires the development of a tissue culture system where interactions between the different types of astrocytes and neuroblasts can be studied. The method we have chosen to obtain adequate quantities of homogenous astrocytes is the derivation of permanent clonal cells with astroglial properties from explant cultures of 8-day post-natal C57Bl mouse cerebella. These cultures acquired “spontaneously”, i.e. without addition of either carcinogens or oncogenic viruses, the capacity to develop into permanent cell lines from which many clones have been derived. Some of these clones synthesize GFAP, a property characteristic of astroglial cells; in addition they do not bind tetanus toxin or the monoclonal antibody A2B5 and they have no oligodendroglial marker such as surface galactocerebroside or myelin basic protein.