A histochemical and ultrastructural study of stored material in neuronal ceroid lipofuscinosis.

A histochemical and ultrastructural study of five cases of neuronal ceroid lipofuscinosis (NCL) revealed the existence of two related lipopigments differing in some tinctorial properties and ultrastructure. Type I pigment is present in all the tissues affected and corresponds to the pigmentary tertiary lysosomes of well known ultrastructure. Type II pigment occurs exclusively in the neurones of lipophilic cerebral grisea, as a component of the so called protein-myoclonic bodies. It shares with type I certain basic tinctorial properties of lipopigment and its lysosomal localization, but differs in other respects. It stains poorly if at all with the PAS and PAF techniques and is markedly metallophilic, azurophilic and positive for protein. Type II pigment is extremely electron-opaque after staining with heavy metals to the extent that they appear practically amorphous. The possibility that type II material is derived from type I pigment is considered. The amount of type II pigment is highly variable. Both types of pigments are present in residual bodies of various shape and size, including spheroids.