S. D. McCormick H. A. Bern T.M. Herndon 1991 <p><span>Effects of prolactin on morphology and numbers of chloride cells in the opercular membrane of seawater-adapted tilapia (</span><i>Oreochromis mossambicus</i><span>) have been examined. Following five daily injections of ovine prolactin at a dose of 10 μg · g body wt</span>⁻¹<span>, blood samples were taken and opercular membranes were removed and stained with a fluorescent mitochondrial dye (dimethylaminostyrylethylpyridiniumiodine), a fluorescent derivative of ouabain (anthroylouabain), and a histological stain specific for the extensive tubular system of chloride cells (zinc-osmium-iodine). Mean plasma osmolarity and sodium increased 23–24% following prolactin injection. An increase in the relative frequency of chloride cells between 20 and 180 μm</span>²<span>&nbsp;in cross-sectional area and a decrease in the relative frequency of chloride cells greater than 180 μm</span>²<span>&nbsp;were observed following prolactin injections. Average cell size decreased 46–70% and cell height decreased 26–38% following prolactin injections. There was no significant change in cell density. Anthroylouabain staining was observed in both prolactin- and saline-injected fish, and no significant effect on Na</span>⁺<span>,K</span>⁺<span>-adenosinetri-phosphatase activity was seen in either opercular membrane or gill tissue. The results demonstrate an effect of prolactin on chloride cell size and provide a morphological correlate for decreased secretory activity of chloride cells following prolactin injections.</span></p> application/pdf 10.1016/0016-6480(91)90032-2 en Elsevier Effects of prolacton chloride cells opercular membrane of seawater-adapted tilapia article