Munemitsu Hoshino

Ultrastructure of adenoid cystic carcinoma

Ultrastructural examinations of adenoid cystic carcinoma (ACC) have revealed that the tumor cells are classified into 2 types, i.e., type A cells (myoepithelial cells) and type B cells (secretory type cells). In ultrastructure, the neoplastic myoepithelial cells are very similar to normal ones of intercalated duct type, and more resistant against irradiation than the secretory type cells. Type B cells, polyhedral in shape, are undifferentiated, and high in nucleocytoplasmic ratio. Some of them show differentiations into glandular, lining epithelia, and secretory activities. Transitions between both cell types are noted. It is suggested that ACC originates from the intercalated duct, and the recurrence results from proliferation of the remaining myoepithelial cells against irradiation. Furthermore, the ultrastructural evidences showing the continuity between the interstitium and the cystic space are documented. This phenomenon may be responsible for formation of the characteristic interstitium of ACC.

Membrane (M) protein of HVJ (Sendai virus): Its role in virus assembly

Abstract The role in virus assembly of membrane or matrix (M) protein of HVJ (Sendai virus) was investigated. When virions were disrupted with alkali Tween 20, nucleocapsids with a sheathlike cover on the surface and a width of approx 33 nm were often obtained, and this sheathlike structure was composed of M protein. Selective aggregation of viral components in vitro was examined. Each viral component was isolated separately from virions by using detergents, and they were mixed with each other in various combinations. The structures which reaggregated were examined for their protein composition, and the results indicate that the nucleocapsid protein does not combine with viral glycoproteins to form a coaggregate unless M protein is present, which suggests that the M protein in vivo may be a mediator for the association of nucleocapsid with the modified areas of plasma membrane which will become viral envelope.

Studies on the role of M protein in virus assembly using a is mutant of HVJ (Sendai virus)

Abstract A temperature-sensitive mutant of HVJ, HVJ cl.151, was isolated from BHK cells persistently infected with HVJ and characterized. HVJ c1.151 virion had an M polypeptide different in apparent molecular weight from that of HVJ wild-type, that is 36,000 and 34,000 daltons, respectively. HVJ c1.151 was blocked in a late function required for virus maturation. M protein antigen of HVJ c1.151 was detected in infected cells by immunofluorescent microscopy only at permissive temperature but not at nonpermissive temperature, although GP and NP antigens were detected at both temperatures. Further, analysis of the infected cells by SDS-polyacrylamide gel electrophoresis showed that viral structural polypeptides P, F 0 , NP, and F and nonstructural polypeptide C were synthesized in infected cells at nonpermissive temperature and these structural polypeptides were incorporated into virions upon temperature shiftdown, whereas polypeptides HN and M, which may be synthesized at nonpermissive temperature, were not able to be incorporated into virions upon temperature shift down. Thus, the temperature-sensitive lesion of HVJ c1.151 is considered to be in HN and M proteins. Membrane fluorescense, immunoferritin electron microscopy, and SDS-polyacrylamide gel electrophoresis of plasma membranes showed that migration of F 0 , and F to the cell surface occurred normally even at nonpermissive temperature. Immunoferritin electron microscopy also demonstrated that the viral glycoproteins which arrived at the plasma membrane were dispersed on the entire surface of the membrane at the nonpermissive temperature and that viral components synthesized at this temperature could not assemble at the plasma membrane. In addition, it was found that antibody-induced redistribution of viral glycoproteins on the surface of cells infected with HVJ c1.151 and incubated at nonpermissive temperature occurred very rapidly; in contrast, such redistribution of viral glycoproteins occurred more slowly and less completely in cells incubated at permissive temperature, suggesting that viral glycoproteins on the plasma membrane of cells at nonpermissive temperature have a high degree of mobility in the plane of the membrane as compared with those on the plasma membrane of cells at permissive temperature. These results suggest strongly that a function which fixes the viral glycoproteins at restricted areas of plasma membrane to form a viral envelope is blocked in HVJ c1.151-infected cells at nonpermissive temperature. Analysis of plasma membrane by SDS-polyacrylamide gel electrophoresis showed that viral glycopolypeptides but no NP were present on membranes isolated from HVJ cl.151-infected cells at nonpermissive temperature in spite of the presence of a large amount of NP in the whole cells, whereas plasma membranes isolated from cells at permissive temperature contained all viral structural polypeptides. The possible roles of M protein of HVJ in formation of the viral envelope and association of nucleocapsid with the envelope during assembly are discussed based on these results.

Polyembryoma of ovary producing alpha-fetoprotein and HCG: Immunoperoxidase and electron microscopic study

Polyembryoma of ovary producing alpha‐fetoprotein (AFP) and human chorionic gonadotropin (HCG) was studied by indirect immunoperoxidase method for AFP and HCG, and electron microscopy. Clinically, this patient showed pseudoprecocious puberty caused by elevated HCG which is synthesized by trophoblastic cells in polyembryoma. She is put under VAC (vincristine, actinomycin‐D, cyclophosphamide) chemotherapy after operation and shows no signs of recurrence including reelevation of serum AFP at five months after operation. Embryoid bodies which we studied correspond to normal embryo at 15‐ or 16‐day stage. Immunoperoxidase study showed that AFP is synthesized by yolk sac cells of the embryoid bodies and HCG is synthesized by syncytiotrophoblastic cells. The finding about AFP synthesis suggests that normal embryo at 15‐ or 16‐day stage may begin AFP synthesis. Electron microscopic study showed that each part of the embryoid bodies had some characteristic structures. Most striking features found in the cytodifferentiation of the embryoid bodies were noticed in some special differentiation of plasma membrane and existence of surface coat. Desmosomes were found in endodermal cells and yolk sac cells. Ectodermal cells were attached to each other by zonulae occludentes and adhaerentes. Microvilli were found in ectodermal cells and yolk sac cells. Two different kinds of surface coat were found in mesodermal cells and lining cells of yolk sac cavity: thin‐layered deposit of electron‐dense material covering the plasma membrane facing intercellular space of mesodermal cells and endodermal cells, and thick‐layered deposit of electron‐dense material which covered the plasma membrane facing yolk sac cavity of endodermal cells and yolk sac cells. Presence of similar characteristic material in RER of yolk sac cells led us to speculate that thick deposit was synthesized by yolk sac cells and secreted into yolk sac cavity. Combined with immunoperoxidase study by light microscopy, we assume that this thick‐layered deposit has some close relation to AFP.

Expression of meta-vinculin associated with differentiation of chicken embryonal muscle cells☆

We confirmed the existence of meta-vinculin, which cross-reacts immunologically with vinculin and has a slightly higher molecular weight than the latter. The immunological cross-reactivity between meta-vinculin and vinculin was confirmed with monoclonal antibodies against vinculin. Furthermore, we found that this protein is present only in either smooth or striated muscle, but is absent in non-muscular tissues and that the expression of this protein is associated with a differentiation of muscle cells either in vivo or in vitro. Microinjection experiments of fluorescently labelled vinculin and/or meta-vinculin into the cytoplasm of cultured myotubes suggested that meta-vinculin may be localized at sites similar to vinculin in muscle cells.

Subunits of NDV: Hemagglutinin and neuraminidase subunits of Newcastle disease virus☆

Abstract When purified Newcastle disease virus (NDV) was treated with deoxycholate (DOC), two major surface antigens of the virus, hemagglutinin and neuraminidase, were released in biologically active form and the respective antigens could be separated by sucrose gradient centrifugation into two distinct bands. The hemagglutinin subunits obtained by the DOC method were reactive with hemagglutination-inhibiting antibody but did not agglutinate red blood cells even after they were freed from DOC by dialysis. Thus, they appeared to be monovalent. However, they acquired the capacity to agglutinate red blood cells, when they were mixed with the top fraction of the sucrose gradient through which the DOC-disrupted virus had been centrifuged, or by the addition of a phospholipid, phosphatidylethanolamine. Electron microscopic examination of the hemagglutinin subunits revealed filamentous structures associated with several projections on both sides. These results suggested that polymerization of the monomeric subunits occurred, not directly end to end, but mediated through the filament which might be phospholipid in nature.

The deep invagination of the inner nuclear membrane into the nucleoplasm in the ascites hepatoma cells

IT has b een well established that the nuclear envelope of the interphase cell, in animals and in some kinds of plants, is composed of two parallel membranes [l, 3, 121. Some morphological evidences suggesting the nuclear-cytoplasmic interrelationships have also been demonstrated in electron micrographs: the existence of continuities between the membranes of the nuclear envelope and those of the endoplasmic reticulum [4, 12, 131; of several types of discontinuities in the nuclear envelope 15, 131; of deep invaginations of double nuclear membranes into the nuclei, engulfing a portion of cytoplasmic materials [2, 71; of protrusions of the outer nuclear membrane [7, 121; of “bleb” formations of nuclei towards the cytoplasm [6, 91; and of annulate’lamellae [lo, 111. The interpretation that the nuclear membrane is another local differentiation of the endoplasmic reticulum was proposed by Watson [la, 131 and supported by Palade [8]. In the course of electron microscopic study of various ascites hepatomas of rats, the author has met the picture showing a new type of the invagination of nuclear membrane into the nucleoplasm, which has not hitherto been recorded. The present

Class distribution of immunoglobulin-containing plasma cells in the stroma of medullary carcinoma of breast

SummaryA class distribution of plasma cells associated with the stroma in twenty-eight cases of medullary carcinoma of the breast was investigated by an unlabeled immunoperoxidase method. The stroma of the medullary carcinomas tested was found to contain predominantly IgG plasma cells except in two cases. Stroma of the other types of breast carcinoma, including ten cases of papillo-tubular carcinoma, five cases of scirrhous carcinoma, and six cases of medullary tubular carcinoma, contained predominantly IgG plasma cells, although few plasma cells were associated with carcinoma tissues in the latter group. Plasma cells associated with control specimens, including normal breast, fibroadenoma, cystic disease, and intraductal papilloma, were found to be predominantly of IgA type. Few carcinomatous epithelial cells contained secretory components in the cytoplasm, while a number of cells positive for secretory components were observed in acinar and ductular epithelia of normal breast tissues and in benign proliferative lesions of the breast. It is suggested that the lymphoid cells infiltrating the stroma of medullary carcinoma represent a sign of host immune response against the carcinoma cells which is related to the well-known favorable prognosis associated with this tumor.

The distribution of endocrine cells in the mucosa of the gastrointestinal tract of the house musk shrew, Suncus murinus (Insectivora)

SummaryThe distribution of endocrine cells in the gastrointestinal tract of the house musk shrew, Suncus murinus (Family Soricidae, Order Insectivora) was studied immunohistochemically. The hormones investigated were gastrin, cholecystokinin (CCK), somatostatin, secretin, glucagon, gastric inhibitory polypeptide (GIP), motilin and neurotensin. In the gastric mucosa, gastrin and somatostatin cells were only found in the pyloric regions, and no other hormonal cell-types were observed. In the intestinal mucosa, the largest number of endocrine cells belonged to the gastrin and glucagon/glicentin cell-types, whereas CCK-33/39 and secretin cells were the least numerous. Numbers of other cell-types were intermediate between these two groups. The gastrin and GIP cells were mostly localized in the proximal portion of the intestine, decreasing in number towards the distal portion. The motilin and CCK-33/39 cells were restricted to the proximal half. The glucagon/glicentin and neurotensin cells were most abundant in the middle portion. The somatostatin and secretin cells, although only present in small numbers, were randomly distributed throughout the intestine. This characteristic distribution of gastrointestinal endocrine cells is discussed in comparison with the distribution patterns of other mammals.

Cells containing Langerhans cell granules in human lymph nodes of "atypical hyperplasia" with fatal outcome and leukemic reticuloendotheliosis.

Langerhans cell granules could be found in atypical histiocytes in lymph nodes of three patients with “atypical hyperplasia” with fatal outcome and one patient with leukemic reticuloendotheliosis. These atypical histiocytes might be derived from immature mesenchymal cells in lymph nodes and the Langerhans cell granules might be induced in these cells by a particular condition. Only one of the Langerhans cell granules seemingly associated with the plasma membrane could be observed in these atypical histiocytes and all of the granules were seen within the cytoplasm. Quite a number of Langerhans cell granules were located near the Golgi apparatus. Several atypical granules very similar to the Langerhans cell granules could also be observed in these atypical histiocytes. These Langerhans cell granules were assumed to be directly derived from the Golgi apparatus and/or derived from the atypical granules which were secreted from the Golgi apparatus. The relationship between the Langerhans cell granules and the microtubules must also be considered, because Langerhans cell granules were found near the centrioles and microtubules.