Exocytosis of residual bodies in a lysosomal storage disease.

Scanning and transmission electron-microscopic study of the livers of 2 kittens suffering from GM2 gangliosidosis revealed discontinuities in the plasma membrane of hepatocytes and Kupffer cells, indicating an attempt by the cells to free themselves of excess lysosomal residues by means of exocytosis. Inclusions morphologically similar to those seen in the hepatocytes were observed in the perisinusoidal space. Openings were seen on all surfaces of the hepatocytes. Such extrusion of lysosomal residues is an example of a mechanism rarely observed in viable metazoan cells.