GILL MORPHOLOGY AND ATPASE ACTIVITY IN THE GOLDFISH CARASSIUS-CARASSIUS VAR AURATUS EXPOSED TO EXPERIMENTAL LEAD-INTOXICATION

The effect of acute lead intoxication (5 mg l-1) on the structure and function of the gills in Carassius carassius var. auratus was studied. The gills absorbed Pb very quickly and the storage increased progressively in the longest treated specimens. Light and electron microscopy observations on gill filaments from unexposed fish showed in organization similar to that described for other teleosteans. Gill histological and cytological alterations induced by lead were detected after 24 h of treatment and became more evident after 48 h. The salient changes were the following: 1) free parts of secondary lamellae increased in length and had irregular outlines; 2) an increased number of mucocytes, prevalently distributed over the superficial layer of the primary epithelium; 3) chloride and epithelial cell ultrastructure were particularly damaged; the degenerating chloride cells were more numerous; 4) K+-NPPase activity was not particularly affected; on the contrary, Ca2+-ATPase increased particularly in chloride cells.