The glomerulus of a stenohaline fresh-water teleost, Carassius auratus gibelio, adapted to saline water. A scanning and transmission electron-microscopic study.

Prussian carp, Carassius auratus gibelio, were maintained in aquaria with a salinity of 15 0/00 for 3 months. More than 90% of the glomeruli disappeared from the tissue as a result of the adaptation to saline water. Kidney tissue was excised and prepared for electron microscopy after perfusion fixation in situ. The fine structure of the renal corpuscle was compared with the normal ultrastructure of glomeruli of control fish from fresh-water aquaria. The main alterations include retraction of the endothelium from the basement membrane, widening of the subendothelial region, folding of the thickened basement membrane and epithelial layer, and the dislocation of slit diaphragms. The findings are discussed in relation to developmental stages of mammalian glomeruli and glomeruli from tissue cultures. The structural changes of the rudimentary glomeruli of the carp kept in 15 0/00 salt water differ from those observed in euryhaline fish from sea water.