Figure 6

Embryonic TCDD exposure reduces oligodendrocyte numbers in the developing hindbrain. (A) Timeline of oligodendrocyte percursor cell (OPC) development and dorsal confocal images of the hindbrain at 48 hpf from transgenic zebrafish carrying fluorescent reporter genes for olig2 and sox10 [Tg(olig2:EGFP; sox10:RFP)]. Expression of olig2 marks oligodendrocyte precursors, oligodendrocytes, and motor neurons. Differentiated oligodendrocytes express sox10, which also marks migrating neural crest cells and other neural crest derived lineages. olig2+ cells were quantified along the midline, laterally and in total for the developing hindbrain of control (B) and TCDD-exposed (C) embryos. (D,E) Co-expression of olig2 driven EGFP and sox10 driven RFP was used to identify and quantify differentiated oligodendrocytes in the hindbrain. Cells were quantified along the midline, where OPCs are located, and in lateral domains containing OPC derived motor neurons and differentiated oligodendrocytes. Statistical significance was determined by Welch’s t-test. *p < 0.05, **p < 0.01. n = 18–20 fish/group across 3 replicates. Anterior (Ant) is left in all confocal micrographs. Scale bar = 100 μm. Magnification = 20x.