Effects of Salinity on Gill Histology in Sailfin Velifera (Poecilia Velifera)

Abstract

Fish live in aquatic areas with varying salinity from fresh water to seawater. Gills are one of the most important osmoregulatory organs for maintaining the salt-water balance. In this study, changes in the gills of velifera (Poecilia sphenops) acclimated to 20, 30, 40, and 50 ppt of saline in the laboratory were examined histologically and immunohistochemically. Mucus cells (MCs), proliferating cell nuclear antigen (PCNA), mitochondria-rich cells (MRCs), and heat shock proteins (HSP70) + cells were marked in the gill tissue, which underwent routine histological procedures, and the severity of histological alterations increase with the increase of the salinity. When the gills were examined histologically, it was determined that there was an increase in cells due to hyperplasia, especially in the primary lamellae. A rapid increase in MC and HSP70 + cell numbers was observed in the 20 and 30 ppt groups. Although PCNA + cells were present in each salinity group, they were observed in the salinity group up to 50 ppt. An increase in the number and volume of MRCs was observed with increasing salinity. Based on the histological and immunohistochemical results, it is thought that the cytological and molecular arrangements of cells in gills of sailfin velifera under different levels of salinity are essential for the regulation of ion and salt balance.