Electron Microscopy of Intranuclear Inclusions Found in Human and Rat Liver Parenchymal Cells

Abstract

PLATE 145Intranuclear inclusions generally concluded to represent a heterogeneous class of bodies are readily distinguishable from nucleoli, fat droplets, crystals, or melanin also found within nuclei. The intranuclear inclusions associated with virus infection have been broadly classified into two types by Cowdry, type A and type B (1). Both A and B inclusions exhibit morphological variations and the few histochemical studies indicate that not all A nor all B inclusions are chemically alike (1-3). The type B inclusion associated with poliomyelitis, Borna disease, Rift Valley fever (1), and salivary gland virus disease (cytomegalia) (4), often appears in cells where no apparent associatlon with virus etiology could be established. This led Cowdry in 1934 (1) to state, "Consequently with these type B inclusions the existence of a virus should not be taken for granted. They may be simply the expression of nuclear modifications occurring not only in some virus diseases but also in many conditions for which viruses are probably not responsible." Typical intranuclear inclusions have been reported to occur spontaneously in liver and kidney cells of several wild mammals and birds (5), in liver cells of "normal stock" mice (6-8), and in tissue culture cells of foetal leptomeninges (3). Similar nuclear inclusions have been experimentally induced by injections of aluminum hydroxide, ferric hydroxide and carbon (9), by lead poisoning and irradiation (10), and treatment with thioacetamide (11, 12).In a cytochemical study of nuclear inclusions of human, rat, and mouse liver with the light microscope (13) the inclusions were found to be round and to vary in size. They were acidophilic, Feulgen negative, and contained variable levels of basophilic material identified as ribonucleic acid, protein, and occa-

The Aging Adult Liver. I. Bromsulphalein and Bilirubin Clearances

“…Morphologic studies on the aging liver would lead one to suspect that there should be marked functional differences with time (1–3). Other studies have shown that the liver changes not only in gross size (2) but also minute structure (3). The general decline of human function with age ordinarily would be assumed to be reflected in the liver (4, 5).…”

Progression and resolution of megalocytic hepatopathy with exocrine pancreatic metaplasia in a population of cultured juvenile striped bass Morone saxatilis

“…Electron microscopic studies by Kleinfeld et al (1956) confirmed that these ~nclusions represented cytoplasmic invaginations into the nucleus. Cytoplasmic organelles were identified within the inclusions and the nuclear envelope was often found to be continuous with the inclusion body membrane.…”

Nuclear Inclusions in Lutein Cells of Pregnant Rats

“…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.…”

“…If such nuclear inclusions of cytoplasmic origin are surrounded by double membranes, they are called pseudoinclusions and are probably formed by a deep invagination of the cytoplasm into the nucleus (KLEINFELD et al, 1956;WESSEL, 1958;ROBERTSON, 1964;FOSTER et al, 1965, GRAY andDONIACH, 1969;HIGASHI, 1969). On the other hand, some nuclear inclusions are naked in the karyoplasm and are called true nuclear inclusions.…”