Inhibitory neuron migration and IPL formation in the developing zebrafish retina.
Bottom Line: Finally, HCs, iACs and dACs each undergo cell type-specific migration.In contrast to current hypotheses, we find that most dACs send processes into the forming inner plexiform layer (IPL) before migrating through it and inverting their polarity.By imaging and quantifying the dynamics of HCs, iACs and dACs from birth to final position, this study thus provides evidence for distinct and new migration patterns during retinal lamination and insights into the initiation of IPL formation.
Affiliation: Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge CB2 3DY, UK.Show MeSH
Mentions: We next turned our attention to iACs. We followed 50 iACs throughout the multipolar phase (Fig. 4A; supplementary material Movie 4). Consistent with a previous zebrafish study (Godinho et al., 2005), multipolar iACs appear to stabilize processes that are in contact with the forming IPL (n=50 cells; Fig. 4A; supplementary material Movies 4 and 5). During stratification, some of these cells were seen to extend short, tangentially directed protrusions and shuffle their somas tangentially (supplementary material Fig. S4A). Out of the 29 iACs we followed with somas situated one or more cell body diameters apical of the IPL at the end of the imaging session, all were seen at least once during the time-lapse period to be directly adjacent to the IPL, only to move away from the IPL later in the movie (Fig. 4A). Thus, it is not the case that iACs simply pile up over the IPL according to their time of arrival as suggested previously (Rapaport, 2006; Voinescu et al., 2009).Fig. 4.
Affiliation: Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge CB2 3DY, UK.