An Electron Microscope Study of Intranuclear Inclusions in Mouse Liver and Hepatoma

Abstract

An electron microscope study of intranuclear inclusions which occur in giant cells in a transplantable mouse hepatoma and in enlarged liver cells in mice fed a diet containing bentonite demonstrates that these inclusions are formed by invaginations of the nuclear envelope, and corroborates a previous histochemical study which revealed that the contents of the inclusions are of cytoplasmic origin.In the hepatoma cells the intranuclear inclusions are abundant, small, and situated close to the border of the nucleus, and there are wide openings from the cytoplasm into the invaginations whose contents include lipid droplets, ergastoplasm, and structurally normal mitochondria.In the enlarged liver cells the inclusions are fewer in number, generally much larger than those in the hepatoma, hence they extend deeper into the nucleus, and the interior is continuous with the cytoplasm through only a small opening. Some normal ergastoplasm is present within the inclusions but all other constituents are abnormal. Both normal and degenerating mitochondria occur in the cytoplasm but only degenerating ones are found within the inclusions.Both types of inclusions arise in greatly enlarged ceils in which an attempt is made to maintain the normal nuclear surface/nuclear volume ratio by the development of the invaginations of the nuclear envelope.

Nuclear pseudoinclusions in melanoma cells: prognostic fact or artifact? The possible role of Golgi phosphoprotein 3 overexpression in nuclear pseudoinclusions generation

“…Interestingly, Leduc and Wilson suggested that NPIs constitute a specific adaptation mechanism related to the apparent reduction of the nuclear–cytoplasmic ratio . The increasing volume of the cell nucleus, particularly of the hyperchromatic, metabolically active cancer cell nucleus may be partly reduced as a result of the nucleoplasm being filled with cytoplasmic elements, which form the NPIs, packed into it.…”

Acute Ultrastructural Alterations in Irradiated Proliferative Chondrocytes of Rat Growth Cartilage

“…They usually present lobulated or multiple nuclei. These nuclear changes were described in many tumors and irradiated tis sues [12,18,19] and had been considered as attempts by enlarged cells to maintain the normal ratio of nuclear surface area to nuclear volume [20], The presence of many binucleated cells can also be explained by the same mechanism in which nuclear division is accomplished without cyto plasmic division.…”

Nuclear Inclusions in Lutein Cells of Pregnant Rats

“…Many kinds of cytoplasmic organelles and products were found in the nucleus, such as the mitochondria (BRANDES et al, 1965;KLUG, 1966;AWAYA et al, 1967;OLIVA et al, 1973), Golgi apparatus (BUCCIARELLI, 1966;BLOOM, 1967), rough endoplasmic reticulum (BLOOM, 1967;LEDUC and WILSON, 1959), centrioles (BLOOM, 1967), free ribosomes (BLOOM, 1967) secretory granules (FOSTER et al, 1965), lipid droplets (LEDUC and WILSON, 1959), Langerhans cell granules (WOLFF and SOLLEREDER, 1969) and dense bodies (NAKAYAMA and NICKERSON, 1972). The mechanism of engulfing such cell organelles into the nucleus was repeatedly discussed by many authors.…”

“…However, the light microscopy cannot distinguish two types of nuclear inclusions, the true inclusion and the pseudoinclusion, which can be discerned only by electron microscopy. Many early studies with the electron microscope on the nuclear inclusions dealt with the pseudoinclusions (KLEINFELD et al, 1956;WESSEL, 1958;LEDUC and WILSON, 1959;ROBERTSON, 1964;FOSTER et al, 1965;GRAY and DONIACH, 1969;HIGASHI, 1969 The true nuclear inclusion is embedded within the karyoplasm without any membranes or fibrous barriers around it. There are two kinds of true nuclear inclusions, one is intrinsic and the other is extrinsic.…”

“…Glycogen particles (HIMES and POLLISTER, 1958;BINGELLI, 1959;CARAMIA et al, 1967), mitochondria (BRANDES et al, 1965;KLUG, 1966;AWAYA et al, 1967;OLIVA et al, 1973), secretory granules (FOSTER et al, 1965), Golgi apparatus (BUCCIARELLI, 1966;BLOOM, 1967), rough endoplasmic reticulum (BLOOM, 1967;LEDUC and WILSON, 1959), centrioles (BLOOM, 1967), annulate lamellae (OLLERICH and CARLSON, 1970;MAUL, 1970), free ribosomes (BLOOM, 1967), lipid droplets (LEDUC and WILSON, 1959), Langerhans cell granules (WOLFF and SOLLEREDER, 1969) and dense bodies (NAKAYAMA and NICKERSON, 1972), all of which are originally cytoplasmic structures, may be enclosed in the nucleus by one or more of several possibilities.…”