Separation of dorsal and ventral dopaminergic neurons from embryonic rat mesencephalon by buoyant density fractionation: disassembling pattern in theventral midbrain

The dopaminergic neurons of the ventral mesencephalon, though physically mi xed with non-dopamine neurons, are organized into dorsal and ventral 'tiers ' with regard to their ontogeny, efferent projections and their relative po sition in the various mesencephalic sub-nuclei. We have employed buoyant de nsity fractionation to separate the dopaminergic neurons of the two compart ments and compare their subsequent phenotype development with respect to th eir expression of the gene encoding tyrosine hydroxylase, the rate-limiting enzyme in the catecholamine biosynthetic pathway. Using immunocytochemistr y, separately and combined with in situ hybridization, we demonstrate here that sedimentation of cell suspensions from E19 rat ventral mesencephalon o n fi-step Percoll gradients produces cell fractions enriched in ventral and dorsal tier DA neurons, respectively. (C) 1999 Elsevier Science B.V. All r ights reserved.