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Biomedical subjects

Y Tanuma

Publications and source records attributed to Y Tanuma.

At least 37 records · Page 2Linked to original sources
PubMed1987

Electron microscopic study on the hepatic sinusoidal wall of the soft-shelled turtle (Amyda japonica) with special remarks on the smooth muscle cells.

The hepatic sinusoids of the soft-shelled turtle (Amyda japonica) were examined by transmission electron microscopy. The sinusoidal wall was composed of endothelial cells, Kupffer cells and Ito cells. The basal surface of the hepatocyte facing the Disse's space was covered by a continuous basal lamina. In addition to the Ito cells, the Disse's space contains a considerable number of smooth muscle cells. Many of these were distributed sporadically, while others appeared as a sphincter circling the sinusoid. The smooth muscle cells in the Disse's space showed the following features: 1) The nucleus was located eccentrically near one end of the cell. 2) The surface vesicles and pits, mitochondria and dense patches along the myofilament bundles were all sparse as compared with those known from mammalian smooth muscle cells. 3) Cytoplasmic processes or ruffles were protruded into the Disse's space. 4) A weak basal lamina could be recognized. Sinusoidal endothelial cells were characterized by many large electron lucent lysosomes in their perikaryon and by small fenestrae in their attenuated cytoplasm. Ito cells sending out several cytoplasmic processes, possessed a single large lipid droplet on one side of the nucleus. A single cilium budding from the distal centriole into the Disse's space was found in an Ito cell. Extrasinusoidal macrophages were considerably numerous in the soft-shelled turtle liver. Some of the macrophages were apparently migrating into the sinusoid, there to presumably transform into the Kupffer cells.

Adipose Tissue↗
PubMed1984

A transmission electron microscopic study on sinusoidal cells of guinea pig liver, with special reference to the occurrence of a canalicular system and "pored domes" in the endothelium.

Hepatic sinusoidal cells in the guinea pig were examined by transmission electron microscopy (TEM). A meandering canalicular system was detected in the sinusoidal endothelial cell both in thicker portions of cytoplasmic extensions and in small areas of the perikaryon. It consisted of meandering canaliculi with vacuolar expansions and constrictions, which penetrated the endothelial cytoplasm, forming as a whole a network. The canaliculi possessed more than two openings which usually communicated with the sinusoid, but occasionally poured themselves into the Disse's space. This network of canaliculi seems to permit infiltration of blood plasma. The "pored domes" recorded by Fujita and his collaborators on the glomerular endothelium of the rat and rabbit kidney were also revealed on the perikaryonal cytoplasm of the sinusoidal endothelium of guinea pig liver. Osmium-blackened lipid droplets were found in the sinusoidal endothelium, which suggested the release of lipid into the sinusoid. Short-term administrations of excessive vitamin A exerted no influence on the endothelial lipid droplets. The guinea pig is a rodent species which stores a very small amount of lipid droplets in its fat-storing cells and the so-called empty fat-storing cells were frequently detected. A single cilium was often found in the fat-storing cells in the guinea pig as in other species.

Animals↗
PubMed1983

Electron microscopic studies on the sinusoidal cells in the monkey liver.

The sinusoidal wall was observed by transmission electron microscopy in crab-eating monkey livers. The perikarya of sinusoidal endothelial cells were characterized by numerous macropinocytotic vacuoles and curved smooth-surfaced tubules of high electron density. Size and spacing of fenestrae in endothelial sieve plates corresponded to essentially those in other mammalian species including the human. It was verified that the high concentration of microfilaments was responsible for the electron dense appearance of the sieve plate in tangential sections. Besides occasional overlapping of endothelial sheets, complicated interdigitations of several short lamellae originating from endothelial processes occasionally caused a layered structure of the endothelial lining. Kupffer cells were strikingly rich in lysosomes and contained large mitochondria and phagosomes. They were fixed to the endothelial lining by patches of junctional complexes identical with those between endothelial cells. Ito cells of the monkey liver demonstrated, like those of the human liver, many smooth-surfaced caveolae and vesicles along their perisinusoidal surface, suggesting their micropinocytotic activity. They also contained glycogen beta-particles which were partly gathered around lipid vacuoles. The electron dense droplets enclosed by glycogen particles as revealed in human Ito cells and regarded as immature lipid droplets retaining the chemical properties of glycogen, could rarely be confirmed in the present study. Between the Ito cell and hepatocyte there occurred many junctional complexes. The space of Disse contained, besides abundant collagen fibrils, numerous fine filaments forming irregular meshworks or bundles which resembled fibrillar material (precursor of collagen) in appearance in the dilated cisternae of the rough endoplasmic reticulum (RER) of the Ito cell. These filaments often entwined the collagen fibrils in the Disse's space as if to participate by apposition in their development. The question, whether pinocytosis-like structures of the Ito cell might be involved in the precursor transport from the cisternae of the RER to the Disse's space, remained unanswered.

Adipose Tissue↗
PubMed1983

Occurrence of crystalloids in the sinusoidal endothelial cell of a crab-eating monkey liver.

An electron microscope examination of the liver of the crab-eating monkey revealed small crystalloids occurring occasionally in the thicker portion of the cytoplasmic extension of the sinusoidal endothelium. They were uniformly encased in a membrane sac which was mostly smooth-surfaced but was at several points continuous to ribosome-studded cisternae of the RER. The crystalloids were mostly polygonal in configuration and were classified into three types. Type I crystalloids, according to the grade of the complexity of their composition, represented the simplest, or original, form and were composed purely of a compact bundle of tubules measuring about 300 A in diameter. Types II and III crystalloids were composed of tubules and an electron lucent matrix. In type II crystalloids, the tubules were embedded parallel to one another in two sets of matrix layers which crossed each other at a right angle, while in type III, the matrix layers embedding the tubules cut each other at about 70 degrees. The crystalloids are presumed to have developed from a substance synthesized in the cisternae of the RER in the sinusoidal endothelial cell and their investigation may aid in elucidating the proteinic products of this RER-rich cell which have thus far remained-under dispute.

Animals↗
PubMed1982

Further electron-microscope studies on the human hepatic sinusoidal wall with special reference to the fat-storing cell.

In biopsy specimens from two normal human livers, fat-storing cells and Kupffer cells were observed by electron microscopy with the following results: 1) In the human Ito cells numerous micropinocytotic caveolae and vesicles occurred either scattered beneath the plasma membrane or fused into short tubules. In the cytoplasm abutting on these structures, minute clusters of glycogen beta-particles were revealed which presumably had been synthesized in the local cytoplasm from carbohydrate (glucose) ingested by pinocytosis. 2) Lipid droplets (vacuoles) were formed within the accumulations of the glycogen beta-particles. These findings support the view that the glycogen synthesized in the Ito cells may represent a transitional compound in the process of lipid synthesis from carbohydrate. 3) Among lipid vacuoles, electron-dense droplets equally large were found, often containing electron-lucent areas in their center. On the surface of these dense droplets, compact clusters of glycogen particles adhered as if they might have permeated into the droplets. These droplets may possibly be immature lipid droplets retaining chemical properties of the glycogen in their superficial part; they remained insoluble during the preparation procedures for ultrathin sections. 4) The occurrence of the worm-like structure has for the first time been revealed in the human Kupffer cells. Besides its short tubular profiles, a more complex structure was demonstrated.

Female↗
PubMed1982

Electron microscopic observations on single cilia in the intrahepatic biliary ducts in some birds.

The intrahepatic biliary passage in five species of birds was investigated with the transmission electron microscope. The avian liver was characterized by a frequent occurrence of intralobular bile ductules and canaliculo-ductular junctions in the parenchyma. It was further characterized by solitary bile ductular epithelial cells intercalated among hepatocytes surrounding bile canaliculi. The present study first revealed that avian bile ductular epithelial cells possess a long single cilium. Its basal body (distal centriole) was connected to a basal foot and slender rootlet and accompanied by a proximal centriole. The hepatocytes facing the bile passage possessed no cilium, although they frequently had a diplosome in their apical cytoplasm. The single cilia of the bile ductular epithelium gradually tapered toward the tip. The original fiber pattern in the most proximal part was peripheral 9 doublets +0. In the ciliary shaft, the doublets altered into singlets which were diminished in number gradually toward the distal parts of the shaft, so that in the tip only one singlet remained. Since these fiber patterns in the single cilia markedly deviated from the 9 + 2 fiber pattern of the ordinary motile cilia, they may not be motile, but properly regarded as sensory or chemoreceptors.

Animals↗
PubMed1982

Electron microscopic study on the sinusoidal wall of the liver in the flatfish, Kareius bicoloratus: demonstration of numerous desmosomes along the sinusoidal wall.

The liver of the flatfish, Kareius bicoloratus was observed by transmission electron microscopy. The hepatocytes surround the bile canaliculi and are loosely disposed with few connections in between. The architecture of the hepatic tissue is first supported by junctional complexes between hepatocytes abutting on the bile canalicular lumen, second, by intraparenchymal bile ductules connecting with hepatocytes through desmosomes and third, by particular "desmosomal complexes" composed of numerous desmosomes arranged along the interhepatocytic space and accompanied by bundles of microfilaments in the cells. The fourth, and most important supporting factor of the hepatic tissue, consists of sinusoidal cells including adjacent hepatocytes connected by many desmosomes. The Disse's space lacks collagen fibrils but contains filaments of type IV collagen. Sinusoidal cells are reinforced by abundant microfilaments in their cytoplasm. Desmosomes occur between endothelial cells, which are further connected by other desmosomes to hepatocytes as well as Ito cells. Desmosomes are most numerous around the Ito cells. Thus, the cells forming the sinusoidal wall are interconnected by many desmosomes, forming as a whole a strong framework which supports the hepatic tissue. The desmosomes between the sinusoidal cells are characterized, except for those between endothelial cells themselves, by the presence of zones of microfilaments on both of their sides which extend parallel to the desmosomal plaques and are believed to strengthen the desmosomal connection. No Kupffer cells could be identified in the sinusoid, but macrophages were demonstrated in the parenchyma near the Disse's space.

Adipose Tissue↗
PubMed1981

An electron microscopic study of the kitten liver with special reference to fat-storing cells.

In a 67-day -old female kitten, the morphological differentiation of the hepatic parenchyma has been electron microscopically examined. 1)In spite of the advanced ultrastructural differentiation of the hepatocyte, the usual location of the Golgi complex to the apical cytoplasm around the bile canaliculus has not yet been established. Numerous mitochondria are mingled with round microbodies characterized by a marginal plate and a crystalloid core. Tubular cisternae of the SER occur only around the microbodies and lack within the accumulation of glycogen alpha-particles. 2)The sinusoidal lining has been fully differentiated and is composed of the "cytoplasmic processes" and the "sieve plates" whose fenestrae average 13300 A in diameter. 3) Kupffer cell shows an active phagocytosis to blood cells. The fuzzy coat is unsatisfactorily preserved. The cytoplasm occasionally shows short segments of a worm-like body. 4) The fat-storing cell (FSC) contains a small amount of lipid droplets which mostly appear within the dense accumulation of glycogen beta-particles. Also empty FSCs devoid of lipid droplets mostly possess glycogen accumulations. The glycogen accumulations enclosing lipid droplets are closely juxtaposed by cisternae of the RER and mitochondria, suggesting the possible involvement of these organelles as well as glycogen in the lipid synthesis in the FSC. In most FSCs, abundant cisternae of the RER are dilated and filled up with a finely flocculent material, suggesting an active production of collagen precursor. The FSCs possess abundant microfilaments and microtubules. A single cilium is issued into the Disse's space from one of the paired centrioles located in the Golgi area. 5) The Disse's space of the kitten contains, besides FSCs, plasma cells and macrophages. The latter agree in ultrastructure with the Kupffer cells and are assumed to be transformed into them by being incorporated in the endothelial lining of the sinusoid.

Animals↗
PubMed1980

Electron microscope observations on the intrahepatocytic bile canalicules and sequent bile ductules in the crucian, Carassius carassius.

In the hepatic parenchyme of the crucian, Carassius carassius no interhepatocytic bile canaliculi are detected, but each hepatocyte possesses a single intracellular bile canalicule filled with microvilli protruded from the hepatocyte. The intrahepatocytic bile canalicule originates at the neighborhood of the nucleus to extend to the cell surface where it empties into the intraparenchymal biliary passage running in the interhepatocytic space. The pericanalicular cytoplasm contains many small vacuoles which have possible been elaborated in Golgi complexes and may be discharged by emiocytotic mechanism into the canaliculus, suggesting bile secretion in the crucian liver. The intercellular biliary passage consists of the terminal bile ductule composed of two elongated flat epithelial cells enclosing a narrow and twisted lumen in between; the secondary or middle-sized ductule is surrounded by three cuboidal epithelial cells, and the large bile duct by five or more cuboidal cells and a smooth muscle layer. The basal lamina is detected only in the middle-sized ductule and in the large duct. The intracellular bile canalicules attached to the proximal bile ductule by means of the junctional complex are classified into the "terminal" and "side bile canalicules"; they are attached to the proximal end and the lateral wall of the terminal bile ductule, respectively. The ectoplasmic layer bordering the intracellular bile canalicule is rich in microfilaments which partially enter microvilli, and the epithelial cells of the intercellular biliary duct system are also characterized by abundance of microfilaments. These probably contractile cytoplasmic filaments may control or accelerate bile flow through intrahepatic biliary passages. The periductular or periductal cells closely apposed to intercellular bile passages are thought to be mesenchymal cells such as fibroblasts among which histiocytoid elements are intermingled.

Animals↗
PubMed1978

Electron microscope study on the hepatic sinusoidal wall and fat-storing cells in the bat.

The three cell types known to form the hepatic sinusoidal wall were electron microscopically observed in three kinds of bats captured in winter and summer. 1. The cytoplasmic extensions of sinusoidal endothelial cells consisted of continuous thicker parts ("cytoplasmic processes") and discontinuous thinner parts ("sieve plates"). The alternate disposition of the two parts was rather irregular, and the sizes, shapes and spacings of the fenestrae were variable. In the thinner parts with numerous small fenestrae, larger gaps were also mingled. The endothelium was simple-layered and devoid of basal lamina. Interendothelial junctions were found mainly between closely apposed margins of the "cytoplasmic processes" and agreed in structure with the "junctional complex" of WISSE (1970). 2. Kupffer cells, morphologically distinct from the endothelial cells, bulged strongly into the sinusoidal lumen. Provided with many microvillous pseudopods, they were stellate in appearance. They were fixed to the endothelial lining by small junctional areas which occurred between the Kupffer cell body and the "cytoplasmic processes" of the endothelium. 3. Fat-storing cells were located in the Disse's space. They generally contained only smaller amounts of lipid in a few droplets. So-called empty fat-storing cells were numerous, especially in winter bats. The perikaryonal cytoplasm revealed a large Golgi complex and well-developed granular endoplasmic reticulum. The three mesenchymal cell types of the sinusoidal wall possessed the centriole in common within the Golgi complex, but only the fat-storing cell was provided with the single cilium. Fat-storing cells extended cytoplasmic processes ramifying beneath the endothelial lining occasionally surrounding the sinusoids almost completely, and which seemed to reinforce the endothelial lining and to bring about the constriction of the sinusoid. In hypervitaminotic bats that daily received 6,000 I.U. vitamin A for three days, remarkable increase in size and number of lipid droplets was observed in slightly hypertrophic fat-storing cells, and the empty cells disappeared simulating an increased number of fat-storing cells. Suggestion was made of an antidotal function of fat-storing cells against excess vitamin A which might be considered a toxic agent in the broad sense. 4. The Disse's space of bat liver contained plasma cells, lymphocytes and macrophages, the latter too often being under migration through the endothelial fenestrae.

Animals↗
PubMed1978

Fine structure of the Kupffer cell in the bat, with special reference to the worm-like bodies.

The livers from normal bats captured in summer and autumn (active period) and in winter (hibernating period) were electron microscopically examined with reference to the worm-like bodies. 1) The worm-like bodies were numerous in bats captured in the active periods, while they were few in hibernating bats. The development of this body varied considerably from cell to cell. 2) The worm-like body seemed to develop from a short and straight tubular invagination of the plasma membrane, whereas the fully developed unit of the body comprised a twisted and complicatedly branching tubule extended in the cytoplasm, the end of which seemed to be retained as the orifice to the extracellular space. The contents of the tubule continuous with the cell coat showed faint transverse striation and a median dense line. A large worm-like body was presumably composed of a number of the units tangled complicatedly with each other, showing a large accumulation of abundant profiles of closely packed tubules. In some Kupffer cells a long tortuous tubule with a median dense line penetrated the cytoplasm transversely and communicated at both ends with two opposite surfaces facing the sinusoid. 3)The cytoplasmic area of the worm-like bodies was almost completely devoid of organelles; no communication between the worm-like bodies and other organelles was recognized. This finding suggested the resemblance of the area of the worm-like bodies to the ectoplasm. This assumption also was supported by frequent occurence of large coated vesicles along the worm-like bodies often communicating with them. 4)The worm-like bodies did not show any signs of enlargement even in Kupffer cells ingesting blood cells in their phagocytic vacuoles. Their profiles were found abutting on the phagosomes, but direct communication between both structures was not found. 5)It was proposed in this study that the worm-like bodies might possibly represent a membrane reservoir and contribute to the enlargement of the Kupffer cell surface.

Animals↗
PubMed1978

Transmission electron microscope observation of epithelial cells with single cilia in intrahepatic biliary ductules of bats.

Cells with long single cilia arising from basal bodies in the apical cytoplasm were occasionally revealed in the bile ductular epithelia of bats (Miniopterus schreibersi (Kuhl), Myotis macroductylus (Temminck) and Rhinolophus cornutus (Temminck)). The basal body (distal centriole) was associated witha proximal centriole, so the basal structure was of "two centriole type." In cross sections of the long tapering cilia the arrangement of cilary microtubules was determined. In the most proximal portion of the cilia doublet microtubules were arranged in the 9+0 pattern, while in more distal portions alteration and diminution of the doublet fibers occurred, splitting entirely into single microtubuli which were most frequently rearranged in the 6+1 or 7+1 pattern. The occurrence of the 9+0 fiber pattern and the basal structure of "two centriole type" suggested that the biliary ductular cilia might be sensory or chemoreceptive in nature and not motile. Similar cilia are expected to be found distributed widely in the epithelia of excretory ductal system of large exocrine glands of vertebrate species.

Animals↗
PubMed1978

Occurrence of centrioles in interphasic hepatocytes of bat and chicken.

Occurrence of centrioles in non-dividing hepatocytes was examined by electron microscopy in the bat, Miniopterus schreibersi (Kuhl) and Myotis macrodactylus (Temminck), and the chicken. In both species centrioles were mostly found in the apical hyaloplasmic halo which was distinct in the chicken but rather indistinct in the bat. There was no difficulty in locating centrioles in the hepatocytes of either species. In the chicken centrioles were found in the attenuated apical cytoplasmic areas of 4-6 hepatocytes surrounding the bile canaliculus, giving us the impression that the occurrence of centrioles in non-dividing hepatocytes might be more frequent in the chicken than in the bat. The centrioles found in non-dividing bat and chicken hepatocytes apparently formed diplosomes. Neither multiple centrioles (comprising more than three) nor centriolar replications were found. Single cilium formation from the centrioles was not observed in either species.

Animals↗
PubMed1976

Possible function of human brown adipose tissue as suggested by observation on perirenal brown fats from necropsy cases of variable age groups.

In 134 out of 180 perirenal fat samples (74%) derived from Japanese necropsy cases aged from 1 month to 86 years, the brown fat tissue persisted in variable amounts. Brown fat cells were classified into 6 types: Type 1 cells are fat-depleted cells filled with granular cytoplasm and are believed to be produced after oxidation of fat for heat production. Type 2 cells are small-locular cells suitable for rapid oxidation of fat droplets. Type 3 (middle-locular) and 4 (large-locular) represent fat-storage cells containing large amounts of fat. Type 5 cells are thought to be transitional forms between multilocular brown fat cells and monolocular white fat cells. Type 6 (cytoplasm-rich multilocular) cells, usually found together with Type 1 cells, are thought to be fat-depleting or -consuming cells, since in them fat droplets are reduced in number and size probably in consequence of oxidation of fat, but by contrast granular cytoplasm is increased in amount separating the individual fat droplets by thick cytoplasmic septa. The occurrence of Types 1 and/or 6 cells that has been revealed in 65 out of the total 180 samples (36%), suggests that the oxidation of fat for the thermogenesis proceeds in the brown fat tissue and that brown fat cells partially undergo fat depletion. In the present study, the thermogenesis of human brown fat tissue was suggested chiefly with regard to the occurrence of Types 1 and/or 6 cells. In the majority of perirenal fat samples from infants (1-11 months) relatively numerous Types 1 and 6 cells were frequently revealed together with Type 2 cells, suggesting rapid and active heat production in support of the view that in human infants the brown fat tissue may be thermogenetically active to maintain body temperature. In the same manner, marked ability to produce a considerable amount of heat was evidenced in brown fat tissue of children and teenagers. In younger and elderly adults the frequency of occurrence and the amount of the perirenal brown fat tissue were decreased but Types 1 and/or 6 cells could be found in 17-40% of them, infrequently together, with Type 2 cells, suggesting persistence of the thermogenic activity with occasional large heat production especially in younger adults (20-39 years). Thus, the results obtained in this study have clarified that the human brown fat tissue can respond to stimuli given to the body by oxidation of stored fat even in the latest decades of life. In cases of death from burning, drowning, bleeding, drug poisoning etc., numerous Types 1 and/or 6 cells were found, suggesting that an active fat oxidation would take place in brown fat tissue assumedly as the result of the raised noradrenalin level in this tissue. The so-called small cytoplasmic cells found in perirenal fats from cases of death from liver cirrhosis and other causes were assumed to be atrophic fat-depleted brown fat cells.

Adipose Tissue, Brown↗
PubMed1975

The occurrence of brown adipose tissue in perirenal fat in Japanese.

1. In 125 cases of perirenal fat samples derived from human necropsies (from 1 month to 86 years), the occurrence of the brown adipose tissue was examined. Brown fat cells were contained in 72% (90: 125) of the cases. 2. In the infants, all samples contained maximal amounts of brown fat cells: the perirenal fat was composed almost exclusively of brown fat cells: in children and teenagers they began to diminish, and in younger adults further reductions were observed: after the fifth decade conspicuous diminutions occurred. In later decades the brown fat in the perirenal fat was small in amount. 3. This change in the amount of the brown fat tissue undergoes individual variations. In some cases, the brown fat tissue disappeared from perirenal fats in the early stages of life, while in others it persisted to very late stages of life. A man as old as 86 years possessed brown adipose cells in the perirenal fat. 4. Multilocular brown fat cells were classified into the following types: Type 1, fat-depleted cells: Type 2, small-locular cells: Type 3, middle-locular cells: Type 4, large-locular cells: Type 5, monolocular brown fat cells with a thick cytoplasmic rim and pseudomonolocular brown fat cells and Type 6, multilocular brown fat cells rich in cytoplasm. In the infants, all cell types were identified: the small-locular cells were in general scanty in all decades following infancy: in later decades of life, the most common cell types were middle-locular and large-locular cells. The fat-depleted cell is a particular cell type and may occur usually accompanied by multilocular brown fat cells rich in cytoplasm. 5. The fat lobules are composed of a centrally located brown fat cell area and a peripheral layer of monolocular white fat cells, which in the infants was very thin but in the following ages was gradually widened to invade the interior of the lobules. 6. The present findings suggest a continuous replacement of brown fat cells by white fat cells during advancing age. The monolocular brown fat cell with a thick cytoplasmic rim and the pseudomonolocular brown fat cells probably represent transitional forms between multilocular brown fat and monolocular white fat cells. These cell types were found throughout life, suggesting continuous transformation of the brown fat cell into the white fat cell.

Adipose Tissue, Brown↗