Effects of salinity level on the activity of chloride cell and mucus secreting cell in the gill of the female shortfin molly, poecilia mexicana steindachner, 1863

Abstract

Ovoviviparous poeciliid fishes have been relatively well studied in the unique reproductive strategy, but their osmoregulatory system largely remains unknown. In this study, we conducted a short-term (7 days) lab experiment to investigate the effect of different salinity levels from 0 (freshwater) to 50 ppt (mesosaline) on the number of chloride cells and mucus secreting cells of female Poecilia mexicana. Chloride cells were found at high density along the epithelial lamellae, whereas mucus secreting cells were also concentrated in the gill raker epithelium. More interestingly, the average density of chloride cells and the mucus secreting cell were significantly increased at high salinity levels (P < 0.05). While further validation by immunohistochemistry is warranted, integrative data from our study suggested that the potential function of the osmoregulatory mechanism/strategy was supported by chloride and mucus secreting cells of female P. mexicana gill.