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Biomedical subjects

H Enzan

Publications and source records attributed to H Enzan.

At least 127 records · Page 7Linked to original sources
PubMed1983

Morphologic and radiological observations on the earliest bone marrow formation in human embryos and fetuses.

Morphologic and radiologic studies were undertaken on 26 human embryos and fetuses to determine the stage and site of the earliest bone marrow formation. Up to the 10th week of gestation, primary bone marrow is not present anywhere although the intramembranous ossification occurs in the maxilla and mandible and also in the middle portion of the clavicle. At the 11th week of gestation, X-ray examination showed in two fetuses the bone formation in the clavicle, scapula, maxilla, mandible, and the diaphysis of the long bones. Serial sections of these fetuses revealed that the primary bone marrow occurs first in the middle portion of the clavicle. From a series of our embryological studies, the concept of the mononuclear phagocyte system which involves the bone-marrow-derived monocytic origin of tissue macrophages, is not accepted, at least, on the origin of Kupffer cells in human fetal livers.

Bone Marrow↗
PubMed1983

Fine structure of hepatic sinusoids and their development in human embryos and fetuses.

The fine structure of the hepatic sinusoids of 81 human embryos and fetuses and their development from 5 to 12 weeks gestation were studied. At 5 weeks gestation, sinusoid-like structures and Kupffer-like cells were observed between liver cell cords. Between 6 and 8 weeks gestation the sinusoids were completely developed. Definite Kupffer cells appear at this developmental stage, when the bone marrow has not yet formed. Floating macrophages form cell aggregates in the sinusoids which contact endothelial cells and settle as Kupffer cells. Erythroblastophagia is observed in Kupffer cells and macrophages. The endothelial linings are closed, with the attenuated cell processes and intercellular junctions between the adjoining endothelial cells. No transition was observed between Kupffer cells and endothelial cells. The findings suggest that Kupffer cells in the human embryo are extrahepatic in origin and that they reach the sinusoids via the circulatory system. Ito cells, which store fat, originate from mesenchymal cells in the septum transversum.

Fetus↗
PubMed1982

Mitochondrial damage in galactosamine-induced liver intoxication in rats.

Mitochondria isolated from livers of rats which received D-galactosamine (375 mg/kg body wt., four times) demonstrated a marked decrease in respiratory control ratios, the ADP/O ratios, and state 3 respiration rates and an increase in state 4 respiration rates. The aberration was profound with site I being altered prior to sites II and III. Quantitation of phospholipids revealed a reduction of total phospholipids per mg protein with decreases in phosphatidylcholine and phosphatidylethanolamine contents. Caldiolipin was the only phospholipid which remained unaltered. Fatty acid composition was altered in these phospholipids; caldiolipin was altered most severely, showing reductions in linoleic and arachidonic acids, and an elevation in saturated fatty acids and in some other small components of fatty acids. In phosphatidylethanolamine, palmitic acid decreased, whereas stearic and docosahexenoic acids increased. These changes were smaller in phosphatidylcholine fatty acids. These mitochondria were also characterized by an altered composition in high molecular weight polypeptide components. By experiments with normal mitochondria in vitro, galactosamine, but not other aminohexoses, was proved to be an uncoupling agent of the oxidative phosphorylation system. Electron microscopic observation demonstrated that both in vivo and in vitro treatments with galactosamine induced marked disorganization of mitochondrial structures. These results suggest that mitochondrial damage is also included in galactosamine-induced hepatic lesion.

Animals↗
PubMed1982

DNA template activity in rat brain tumors induced by transplacental administration of ethylnitrosourea.

The ultracytochemical acridine orange (AO) method has been employed to demonstrate DNA template activity within experimental brain tumors induced by transplacental administration ethylnitrosourea (ENU) in Sprague-Dawley rats. Ultrastructural examination revealed that acridine orange binds to DNA exclusively within the active extended euchromatin portion of the cell nucleus of brain tumor and of foci of atypical cell proliferation. No AO reaction products were visible in the non-neoplastic cell nuclei adjacent to the brain tumors. The percentages of AO positive cells in brain tumor cells in rats given an intraperitoneal injection of 3H-thymidine 1 hr before sacrifice were between 2.4% and 8.0%. The average number of AO chromatin reaction products per single section of a cell nucleus varied between 7 and 21. The ratios of areas of euchromatin to heterochromatin were found to be slightly larger in AO positive nuclei then in AO negative nuclei in each of the tumors. The present results suggested that rat brain tumors induced by transplacental administration ENU exhibit de-repression of DNA template normally repressed in the adult state. The usefulness of this method for study on the development of experimental brain tumors is briefly discussed.

Acridine Orange↗
PubMed1980

Light and electron microscopic observations of hepatic hematopoiesis of human fetuses. II. Megakaryocytopoiesis.

Liver tissues obtained from 78 human fetuses between 5 weeks and 10 months of gestation were observed with light and electron microscope. In the third month of gestation hepatic megakaryocytopoiesis reached the maximum level and then appeared to decline. At the maximum level immature to mature megakaryocytes were usually smaller than those from adult bone marrow. They were observed between growing liver cells, within hepatic sinusoids and in the mesenchyme surrounding the liver parenchyma in the given order of frequency. Immature megakaryocytes were characterized by the presence of both demarcation vesicles or tubules and a few small round specific granules. The nucleus was mononuclear but frequently indented. With cell maturation, the megakaryocytes were stained intensely by PAS-technique. The nuclei were multilobulated. Large cytoplasm was dominated by numerous specific granules and well-developed demarcation membrane system. Some megakaryocytes passed through the sinusoidal wall and possibly to hepatic sinusoids. These observations indicate that the main site of hepatic megakaryocytopoiesis may be extravascular and more likely between liver cells. Small megakaryocytes in fetal livers are discussed in relation to the occurrence of similar megakaryocytes in various blood dyscrasias.

Blood Platelets↗
PubMed1978

Adaptive changes of rat liver cells induced by repeated intraperitoneal injections of d-galactosamine. III-Light- and electron-microscopic investigations of hepatocellular cytoplasmic changes.

In rats hepatocellular cytoplasmic changes after daily repeated D-galactosamine (GalN) intoxication--i.e. subacute GalN intoxication--were studied by light and electron microscopy. The number of GalN injections--and thus the days of survival--was between one and 30. The rats were killed six hours after the last GalN injection. Less degenerative changes were found after repeated GalN injections. An increased formation of atypical dense bodies (ADB), a temporary pronounced lipid accumulation and changes of the rough and smooth endoplasmic reticulum were prominent features of subacute GalN intoxication. The implications with respect to a modified GalN action in subacute GalN intoxication are discussed with special reference to biochemical data obtained in the same experimental model (Schuchhardt et al., 1977).

Adaptation, Physiological↗
PubMed1978

Fluorescence and electron microscopic studies on the perivascular mesenchymal cells and fibroblasts after vitamin A administration.

Findings of perivascular mesenchymal cells and fibroblasts in mice receiving large doses of vitamin A were described. Liver, lung, intestine and skin were investigated by fluorescence and electron microscopy. Marked increase of fluorescence of vitamin A was observed in the sinusoidal wall of the liver, in the alveolar septa of the lungs, in the propria mucosa, submucosa and muscular layer of the intestine and in the dermis of the abdominal skin. Increased fluorescence of these organs corresponded, ultrastructually, to the appearance of numerous fat droplets in Ito cells of the liver, septal cells of the lung and fibroblasts of the intestine and of the skin. All of these cells showed the same morphological features and the same distribution in the tissue, namely in the interstitial connective tissue space. These findings indicate that vitamin A storing cells are distributed widely in the connective tissue of various organs and that perivascular vitamin A storing mesenchymal cells and interstitial fibroblasts are probably of common fibroblastic cell line.

Animals↗
PubMed1978

Light and electronmicroscopic observations on hepatic hematopoiesis of human fetuses. I. Granulocytopoiesis in the hepatic mesenchymal tissue.

Focusing on hematopoiesis, especially granulocytopoiesis, livers from ten human fetuses between 7 to 13 weeks of gestation were observed with light and electron microscope. In the hepatic mesenchymal tissue variable number of granulocytes in varying stage of maturation were found from 10 to 13 weeks of gestation. The granules of neutrophils in human fetal livers were classified into three distinct types. The first granules appeared in myeloblasts. The second granules, possibly formed in Golgi complex, were more larger and observed after the promyelocytic stage. The third granules, predominant in mature neutrophils, were pleomorphic. Other than granulocytic, erythrocytic and stromal cells, unclassifiable cells were occasionally encountered. The role of mesenchymal tissues in the granulocytopoiesis, the development of fetal neutrophils and the problem of hematopoietic stem cells were discussed.

Fetus↗
PubMed1977

Adaptive changes of the rat liver cells induced by repeated intraperitoneal injections of d-galactosamine. II. Light and electron microscopic investigations of hepatocellular nucleolar alterations.

The effects of repeated d-galactosamine (GalN) administration - i.e. subacute GalN intoxication - on rat liver cell nucleoli were examined. After an initial intraperitoneal injection of 375 mg GalN/kg body weight the rats were treated with 250 mg GalN/kg body weight daily at intervals between 24 h and 30 days. The rats were sacrificed six h after the last injection by decapitation. Specimens of liver were studied by light and electron microscopy. According to the nucleolar size three stages were to be distinguished. Stage I: decreased nucleolar size after one injection, stage II: increased and maximal nucleolar size after two to five injections, stage III: slightly increased relatively stable nucleolar size after six and more injections. Fine structural observations suggest a nucleolar hyperfunction in subacute GalN intoxication as well as a minor disturbance of the transcription and the transfer of the nucleolar RNA.

Adaptation, Biological↗
PubMed1976

The appearance and degradation of specific hepatocellular cytoplasmic inclusion bodies in rat liver due to D-galactosamine. I. The relation between the amount of liver glycogen and the appearance of the atypical dense bodies in the liver cell.

One of the most sensitive and specific signs of the galactosamine effect upon the rat liver cell is the appearance of PAS-positive and diastase-resistant granules within the cytoplasm of hepatocytes. Light-microscopic, histochemical, biochemical, and electron-microscopic findings reveal that the appearance of these ADB (= atypical dense bodies) depends upon a working glycogen metabolism at the time of GalN treatment. The ADB are composed of particles resembling, due to shape and size, ribosomes and beta particles of glycogen. Most of them are surrounded by the rER, but they are never enclosed by a limiting membrane. Due to sequential changes they can be generally classified into three types; the early, the intermediate, and the late type. In seven experiments it can be shown, that the appearance of the ADB depends upon the time and dosage after GalN treatment. They occur even if an additional treatment with galactose or uridine prevents the liver from the features of a hepatitis, as also shown in the livers of newborn animals up to 3 weeks of age. The histochemical response against various glucosidases, hexosaminidases, pronase, and RNAse as well as against various fixatives indicates that ADB are composed of, at least, two different constituents, the former RNAse-sensitive and visible with routine light-microscopic staining procedures, the latter RNA-resistant, PAS-positive, and invisible after staining with H & E or toluidine blue. The latter is diastase-resistant, suggesting that this portion of ADB does not represent the usual glycoproteins but some abnormal metabolite of glycogen. The ADB can be detected with maximal accumulation in the cytoplasm of hepatocytes at that time when the glycogen content determined in the liver homogenate by biochemical methods is greatly reduced.

Animals↗