Several hypotheses exist to explain their roles in oxygen-chemosensing. In the present
study we assessed the distribution of serotonin, acetylcholine and catecholamines in the
gills of trout (Oncorhynchus mykiss) and goldfish (Carassius auratus) using
immunohistochemistry, and an activity-dependent dye, Texas Red hydrazide (TXR). In fish
the putative oxygen sensing cells are neuroepithelial cells (NECs) and the focus in recent …