BrdU-, neuroD (nrd)- and Hu-studies reveal unusual non-ventricular neurogenesis in the postembryonic zebrafish forebrain

In the postembryonic zebrafish forebrain, subpial locations of neurogenesis do exist in the early cerebellar external granular layer, and unusually among vertebrates - in the primordial pretectal (M1) and preglomerular (M2) Anlagen as shown here with 5-bromo-2'-deoxyuridine (BrdU)/Hu-immunocytochemistry and in situ hybridization of neuroD. An intermediate BrdU incubation time of 12-16 h reveals in addition to proliferative ventricularly located cells those in M1 and M2. This BrdU saturation-labeling shows - in conjunction with a Hu-assay demonstrating earliest neuronal differentiation - that proliferating cells in M1 and M2 represent neuronal progenitors. This is demonstrated by single BrdU-Iabeled and double BrdU-/Hu-labeled cells in these aggregates. Further, expression of NeuroD - a marker for freshly determined neuronal cells - confirms this unusual subpial postembryonic forebrain neurogenesis. (C) 2002 Elsevier Science Ireland Ltd. All rights reserved.