Nuclear inclusions: a study of aging in Drosophila.

Increased numbers and distribution of nuclear inclusions were correlated with aging in Drosophila imagoes. The various types of nuclear inclusions observed in the present study and those reported in the literature were categorized to their morphologies. It was noted that they may be located (a) in the nucleus proper, such as parallel fibrillar bundles, virus-like particles, tubulo-membraneous systems and amorphous fibrillo-granular deposits, (b) between the inner and outer nuclear membranes, such as cytoplasm-like intrusions, multilocular bodies and electron opaque vacuoles, and (c) outside the nucleus proper, such as those cytoplasmic invagination that interdigitate with infoldings of the nuclear membrane. A possible explanation of the relationship of these nuclear inclusions with aging and death is proposed.