The ultrastructural variability of non-specific lipopigments.

Abnormally structured lipofuscin granules found in various cell types of different conditions not related to the neuronal lipofuscinoses (NCL), emphasize the ultrastructural diversity of non-specific lipofuscin morphologically marked by paracristalline inclusions, pseudo-fingerprint enclosures, and stacks of parallel filaments, all of them embedded in the granular matrix of the lipopigments. Though lipofuscin consisting of the regular granulo-vacuolar ultrastructure was also present in many cells of the same tissues, our findings suggest differences, though of unknown biochemical nature, in lysosomal catabolism resulting in varying lipopigment structures within similar cellular compartments.