Mitogenic action of hypoxia upon cutaneous neuroepithelial cells in developing zebrafish.

In zebrafish, cutaneous neuroepithelial cells (NECs) contain serotonin (5-HT) and are believed to initiate physiological and behavioral responses to hypoxia during embryonic and early larval development, when mature gills and O chemoreceptors are not yet present. The number of skin NECs rapidly declines as embryos develop into larvae, but acclimation to hypoxia leads to retention of a greater number of these cells. We hypothesized that reduction of the partial pressure of oxygen (P ) in water would stimulate mitosis in cutaneous NECs in zebrafish.