bluuebunny/crossref_metadata_2025_split huggingface dataset:
Lobular and cellular patterns of early hepatic glycogen deposition in the rat as observed by light and electron microscopic radioautography after injection of 3H‐galactose
Authors: Michaels John E. , Hung Julia T. , Garfield Sanford A. , Cardell Robert R. 
Published: February 2005

AbstractVery low hepatic glycogen levels are achieved by overnight fasting of adrenalectomized (ADX) rats. Subsequent injection of dexamethasone (DEX), a synthetic glucocorticoid, stimulates marked increases in glycogen synthesis. Using this system and injecting 3H‐galactose as a glycogen precursor 1 hr prior to sacrifice, the intralobular and intracellular patterns of labeled glycogen deposition were studied by light (LM) and electron (EM) microscopic radioautography. LM radioautography revealed that 1 hr after DEX treatment, labeling patterns for both periportal and centrilobular hepatocytes resembled those in rats with no DEX treatment: 18% of the hepatocytes were unlabeled, and 82% showed light labeling. Two hours after treatment with DEX, 14% of the hepatocytes remained unlabeled, and 78% were lightly labeled; however, 8% of the cells, located randomly throughout the lobule, were intensely labeled. An increased number of heavily labeled cells (26%) appeared 3 hr after DEX treatment; and by 5 hr 91% of the hepatocytes were intensely labeled. Label over the periportal cells at this time was aggregated, whereas centrilobular cells displayed dispersed label. EM radioautographs showed that 2 to 3 hr after DEX injection initial labeling of hepatocytes, regardless of their intralobular location, occurred over foci of smooth endoplasmic reticulum (SER) and small electron‐dense particles of presumptive glycogen, and in areas of SER and distinct glycogen particles. After 5 hrs of treatment with DEX, the intracellular distribution of label reflected the glycogen patterns characteristic of periportal or centrilobular regions.
The cytoarchitecture of the wall and the innervation pattern of the microvessels in the rat mammary gland: A scanning electron microscopic observation
Authors: Fujiwara Takashi , Uehara Yasuo 
Published: February 2005

AbstractThis report describes the morphology of the smooth muscle cells, pericytes, and the perivascular autonomic nerve plexus of blood vessels in the rat mammary gland as visualized by scanning electron microscopy after removal of connective‐tissue components. From the differences in cellular morphology, eight vascular segments were identified: (1) terminal arterioles (10–30 μm in outer diameter), with a compact layer of spindle‐shaped and circularly oriented smooth muscle cells; (2) precapillary arterioles (6–12 μm), with a less compact layer of branched smooth muscle cells having circular processes; (3) arterial capillaries (4–7 μm), with “spidery” pericytes having mostly circularly oriented processes; (4) true capillaries (3–5 μm), with widely scattered pericytes having longitudinal and several circular processes; (5) venous capillaries (5–8 μm), with spidery pericytes having ramifying processes; (6) postcapillary venules (10–40 μm), with clustered spidery pericytes; (7) collecting venules (30–60 μm), with a discontinuous layer of circularly oriented and elongated stellate or branched spindle‐shaped cells which may represent primitive smooth muscle cells; and (8) muscular venules (over 60 μm), with a discontinuous layer of ribbon‐like smooth muscle cells having a series of small lateral projections. No focal precapillary sphincters were found.The nerve plexus appears to innervate terminal arterioles densely and precapillary arterioles less densely. Fine nerve fibers are only occasionally associated with arterial capillaries. Venous microvessels in the rat mammary gland seemingly lack innervation.
Light‐ and electron‐microscopic observations of the tail bud of the larval lamprey (Lampetra japonica), with special reference to neural tube formation
Authors: Nakao Taisuke , Ishizawa Akimitsu 
Published: February 2005

AbstractSerial transverse and horizontal sections of the tail of the 26‐day larval lamprey, Lampetra japonica, were observed by light and electron microscopy. The axial structures in the tail of the larval lamprey seem to differentiate from the prospective materials derived individually from the tail bud. The latter consists of two closely adjoined cell populations (C1 and C2). C1 is a small cell cluster located posterior to the other group (C2) and consists of loosely arranged polymorphous cells. The cell cluster extends cranially as a cell sheet on the ventral surface of C2; somites differentiate from this cell sheet. C2 is composed of cells elongated mediolaterally and stacked horizontally to form a compact cell mass which is covered on each lateral surface by a basal lamina. The upper one‐third of C2 seems to differentiate into the neural tube, anteceding other axial structures. The middle one‐third of C2 seems to develop into the notochord, and the lower one‐third into the subchord and the undefined cell cord. The central canal develops in the upper one‐third of C2 through the following events: (1) appearance of cilia and a small cavity between adjoining cells; (2) appearance of microvilli in the cavity, in addition to cilia; and (3) development of junctional complexes along the luminal borders of cells surrounding the cavity. Together with these events, cells surrounding the cavity increase in number, acquiring apicobasal polarity and radial arrangement. The cavity itself enlarges by incorporation of periciliary clefts and fusion of cavities with each other to establish the central canal. Near the caudal end of the neural tube, the central canal is directly confluent with the connective‐tissue space through an opening in the dorsal wall of the neural tube.
Relationship between chromaffin cells and blood vessels in the rat adrenal medulla: A transmission electron microscopic study combined with blood vessel reconstructions
Authors: Kikuta Akio , Murakami Takuro 
Published: February 2005

AbstractThe rat adrenal medulla architecture was examined using a combination of medullary blood vessel reconstructions and transmission electron microscopy. The peripheral radicles of the central vein and the medullary capillaries of the medullary arteries were thus precisely identified in the electron microscopic observations. The observations confirmed that the peripheral segments of the central vein were sinusoidal vessels with an attenuated and fenestrated endothelial wall. No ultrastructural differences were observed between segments lined by epinephrine‐storing cells and those lined by norepinephrine‐storing cells. The findings suggest that these peripheral segments of the adrenal central vein were sites of cortical hormonal effects on the adrenal medulla. The vessel structure does not support the hypothesis that medullary chromaffin‐cell development is controlled by selective distribution of adrenal blood vessels.
The effect of dietary consistency on gross and histologic morphology in the craniofacial region of young rats
Authors: Bouvier Marianne , Hylander William L. 
Published: February 2005

AbstractThree groups of weanling rats and three groups of juvenile rats were fed diets which differed in physical consistency for periods of 5 and 8 weeks, respectively. In both the weanling and juvenile rats, one group was fed a soft diet, a second group was fed a hard diet, and a third group was initially fed the soft diet and then was switched to the hard diet for the remainder of the experimental period. The effects of these differences in dietary consistency on gross and histologic morphology of the craniofacial region were examined. Significant differences were found in the dimensions and morphology of the condyle and condylar cartilage as a result of the differences in dietary consistency in both the weanling and juvenile groups. Soft‐diet rats generally had smaller condyles and a thinner layer of condylar cartilage than either hard‐diet or soft/hard‐diet rats. Little change, however, was found in the overall dimensions of the mandible and maxilla in any of the groups of rats.
Genesis of B lymphocytes in the bone marrow: Extravascular and intravascular localization of surface IgM‐bearing cells in mouse bone marrow detected by electron‐microscope radioautography after in vivo perfusion of 125I anti‐IgM antibody
Authors: Osmond D. G. , Batten S. J. 
Published: February 2005

AbstractThe role of mammalian bone marrow in generating surface IgM (sIgM)‐bearing B lymphocytes is reviewed. Precursor cells in the marrow give rise to large, rapidly dividing cells bearing free cytoplasmic μ chains (cμ). The progeny of the large cμ+ cells form a population of small, nondividing cμ+ cells that mature into small lymphocytes, progressively expressing sIgM and other B‐cell surface membrane components. Newly formed sIgM+ cells soon migrate through the bloodstream to the spleen and other lymphoid tissues, where they may die after a short lifespan or be activated to produce antibody molecules. The large‐scale lymphocytopoiesis in the bone marrow thus maintains a population of rapidly renewed virgin B lymphocytes in the peripheral lymphoid tissues. This process continuously creates and selects B cell clones with the wide range of antibody specificites necessary to mediate primary humoral immune responses through postnatal life.A technique for perfusing radiolabeled anti‐IgM antibodies in young mice has now permitted sIgM+ cells to be detected radioautographically in histological preparations of bone marrow under the electron microscope. Small sIgM+ lymphocytes are situated either singly or in small groups throughout the extravascular hemopoietic compartment of the bone marrow, often near sinusoid walls adjacent to late erythroblasts and reticular cells. Some regional concentrations of sIgM+ cells are apparent. sIgM+ cells also appear in transit through the sinusoidal endothelium and are markedly concentrated in the lumen of some sinusoids. Intrasinusoidal sIgM+ small lymphocytes have high densities of sIgM and long microvilli, on which sIgM molecules are concentrated. These studies reveal the localization and cell associations of specifically identified sIgM+ small lymphocytes in the extravascular marrow compartment and suggest that these cells may also undergo a transient intravascular storage and maturation phase. Use of this in vivo immunolabeling technique to detect other cell‐surface markers may further elucidate the microenvironmental basis of B lymphocyte genesis in the bone marrow.
Life history of cells mediating natural resistance to tumor cells and bone‐marrow transplants: The respective roles of cell lineage commitment and host environment in determining strain characteristics of natural resistance to foreign marrow grafts
Authors: Miller Sandra C. 
Published: February 2005

AbstractA class of cells present in the blood and lymphoid tissues of mammals produces rapid cytolysis of tumor cells on first contact. Abundant evidence suggests that such natural killer (NK) cells play a role in tumor immunosurveillance in vivo. A similarly prompt and spontaneous activity can cause the rejection of foreign marrow transplants. These phenomena are known collectively as natural resistance. The cells mediating natural resistance are lymphoid in morphology, but are neither T nor B lymphocytes. Kinetically, NK cells and cells mediating natural resistance to foreign marrow grafts are themselves nondividing but are rapidly renewed from radiosensitive proliferating precursors in the bone marrow. They appear to have no long‐lived (memory) component. Newly formed NK cells have a short residence time in the spleen. Other general properties of the natural‐resistance cell lineage, including strain variation, ontogeny, and cell phenotype, are reviewed in this article. The present study aimed to examine the respective roles of cell lineage commitment and of the host environment in determining strain characteristics of natural resistance to foreign marrow grafts. Chimeras produced by inoculating mice of a strain that normally has little or no natural resistance with bone marrow from adult mice of a highly resistant strain develop resistance to a third‐party marrow allograft. Such chimeras do not develop the full rejection capacity of the high‐resistance strain, however; and chimeras created by inoculating marrow from infant mice develop less resistance than those reconstituted by bone marrow from adult mice. The results demonstrate that the ability to reject foreign marrow grafts develops as an intrinsic property of the natural‐resistance cell lineage. The host environment may provide an additional influence, however, particularly in the initial development of natural resistance in early postnatal life.
Tissue localization and retention of antigen in relation to the immune response
Authors: Tew J. G. , Mandel T. E. , Phipps R. P. , Szakal A. K. 
Published: February 2005

AbstractAntigen persists for months or even years in lymphoid tissues of immune animals and this antigen is believed to participate in the induction and maintenance of B‐cell memory as well as in the maintenance of serum antibody levels. In the present report we describe the phenomenon of antigen localization and long‐term retention on mouse follicular dendritic cells (FDCs). The antigens used were injected in the hind footpads of immune mice and the popliteal lymph nodes were the lymphoid organs generally studied. In addition to presenting the morphological features of mouse FDCs, we report the results of a study of the mechanism of antigen migration from the site of initial localization in the lymph node subcapsular sinus to the regions of follicular retention in the cortex. The migration was followed by light and electron microscopy. The results support the concepts that immune complexes are trapped in the subcapsular sinus and are transported by a group of nonphagocytic cells to follicular regions. The mechanism of transport may involve either migration of pre‐FDCs with a concomitant maturation into FDCs, or cell‐to‐cell transport utilizing dendritic cell processes and membrane fluidity; or a combination of the two mechanisms may be in operation.
Cellular basis of graft‐versus‐host reactions
Authors: Clancy John 
Published: February 2005

AbstractThe biologic basis of Graft‐Versus‐Host Disease (GVHD) is presented as an extremely complex immunopathologic syndrome that involves interaction between many different donor and host cell types. A model of acute lethal GVHD was employed where adult unirradiated (DA X LEW)F1 rats were injected with LEW spleen and lymph node cells. Controls received the same dose of syngeneic cells. At intervals from 2 to 21 days after cell injection, GVHD and control animals were killed and nonadherent cell suspensions prepared from their lymph nodes, spleen and peripheral blood. Cell suspensions were treated with LEW‐anti‐DA‐alloantiserum or normal LEW serum and then analyzed for sIgM+ (B cells), W 3/13+ (T cells), and IgG‐Fc receptors (FcR). Evidence is discussed for the selective removal of host cells with the alloantiserum. In addition, the level of naturally cytolytic (NK/NC) cells was assessed by adding GVHD and control nonadherent lymphoid cells to heterologous lymphoma and sarcoma target cells. Evidence is presented that during acute GVHD, in this parental →F1 combination, there is an early increase within most compartments of donor as well as host W 3/13+ and W 3/13+FcR+ cells. NK/NC cells are increased as well at day 7. During middle stages of acute GVHD, host sIgM+ cells predominate. Late‐stage acute GVHD rats contain few donor and host W 3/13+FcR+, and NK/NC cells but many null cells most of which are FcR−. The importance of unraveling the nature of donor‐ and host‐cell interactions occurring during acute GVHD, which result in rats whose lymphoid tissues are severely depleted of all nonadherent lymphoid cells but FcR− null cells, is discussed.
Influence of colchicine and vinblastine on the intracellular migration of secretory and membrane glycoproteins: I. Inhibition of glycoprotein migration in various rat cell types as shown by light microscope radioautography after injection of 3H‐fucose
Authors: Bennett G. , Parsons S. , Carlet E. 
Published: February 2005

AbstractPrevious studies have shown that colchicine and vinblastine inhibit secretion in many cell types by interrupting the normal intracellular migration of secretory products. In the present work, radioautography has been used to study the effects of these drugs on migration of membrane and secretory glycoproteins in a variety of cell types. Young (40 gm) rats were given a single intravenous injection of colchicine (4.0 mg) or vinblastine (2.0 mg). At 10 min after colchicine and 30 min after vinblastine administration, the rats were injected with 3H‐fucose. Control rats received 3H‐fucose only. All rats were sacrificed 90 min after 3H‐fucose injection and their tissues processed for light microscope radioautography.Examination of secretory cell types such as ameloblasts and thyroid follicular cells in control animals revealed reactions of approximately equal intensity over the Golgi region and over extracellular secretion products, while in drug‐treated rats most of the reaction was confined to the Golgi region. In a variety of other cell types, including endocrine cells (e.g., hepatocytes) and cells generally considered as nonsecretory (e.g., intestinal columnar cells), reaction in control animals occurred both over the Golgi region and over various portions of the cell surface. In drug‐treated animals, a strong Golgi reaction was present, but reaction over the cell surface was weak or absent.These results indicate that in many cell types, colchicine and vinblastine inhibit migration out of the Golgi region not only of secretory glycoproteins, but also of membrane glycoproteins destined for the plasma membrane.
Development of elastic fibers of nuchal ligament, aorta, and lung of fetal and postnatal sheep: An ultrastructural and electron microscopic immunohistochemical study
Authors: Fukuda Yuh , Ferrans Victor J. , Crystal Ronald G. 
Published: February 2005

AbstractThe morphogenesis of elastic fibers of the nuchal ligament, aorta, and lung of sheep was studied by light microscopy, transmission electron microscopy, and immunohistochemical methods for the detection of elastin. The degree of maturation of the amorphous materials of elastic fibers was assessed morphologically in preparations stained by the tannic acid and periodic acid methenamine‐silver methods. With both of these methods, the amorphous components of mature fibers stained less intensely than did those of immature fibers. Elastic fibers in early stages of development consisted of many microfibrils and few, small, branching masses of immature amorphous material. Thicker fibers were formed by the coalescence of growing masses of amorphous materials. In late stages of formation of elastic fibers, the mature amorphous materials were associated with few microfibrils; and they were partially surrounded by immature amorphous materials associated with many microfibrils. Antielastin antibody reacted evenly with amorphous materials in very early stages of elastic‐fiber development, but reacted only with the other zones of amorphous materials in later stages; it also reacted with the microfibrils in all stages. These findings were interpreted as indicating that the microfibrils were associated with small amounts of elastin on their surfaces. This conclusion is in agreement with ultrastructural observations showing (1) that development of microfibrils precedes that of the amorphous material and (2) that the microfibrils adjacent to the immature amorphous materials are covered with small amounts of tannnic acid‐positive amorphous materials. These observations suggest that microfibrils serve as sites for elastin deposition, both in early elastogenesis and in subsequent growth of elastic fibers. However, the nature of the interaction between elastin and microfibrils remains unknown.
Functional anatomy of the peripheral olfactory system of the african lungfish Protopterus annectens owen: Development of the primary olfactory pathway during postembryonic growth
Authors: Derivot Jacques H. 
Published: February 2005

AbstractSeven specimens of the African lungfish ranging in size from 4 to 350 gm were used for the study of changes in the olfactory nerve and bulb during postembryonic growth as expressed by the increasing number of lamellae of the olfactory organ. Serial semithin sections were used, and the data were studied mathematically. The number of axons of the olfactory nerve, the surface area of the bulb, and the number of mitral cells increase exponentially; the mitral cell density decreases exponentially; and the calculated average convergence (counted axons/counted mitral cells) of axons onto the cells of the bulbar relay increases exponentially. Convergence figures obtained are smaller than those cited by other authors; two factors might explain this: first the mode of calculation, and second the fact that every year this fish undergoes a 6‐month starvation stage marked by degeneration of the primary olfactory structure. A preliminary view of the primary olfactory pathway using serial‐section reconstructions is proposed: An orderly projection of the mucosa onto the bulb takes place after a 90° rotation of the system of two perpendicular axes which apply to both the olfactory organ and the olfactory bulb. This study suggests an original attempt at relating the postembryonic change in convergence and projection to the primary processing of the olfactory message.
Structure, development, and cytochemical properties of the nucleolus‐associated “round body” in rat spermatocytes and early spermatids
Authors: Schultz M. C. , Hermo L. , Leblond C. P. 
Published: February 2005

AbstractThe “round body,” a spherical structure typically associated with a nucleolus in male germ cells of the rat, has been examined in the electron microscope using routine and cytochemical methods to determine its structure, composition, and mode of development. Cytochemical analysis indicates that the round body includes neither nucleic acid nor lipid, but is composed of nonhistone protein which appears in the form of 1.6‐nm‐wide fibrils. Development begins in late leptotene, when a single round body appears in each spermatocyte as an irregular spheroid located along the inner surface of the nuclear envelope. During subsequent stages of the meiotic prophase, the round body leaves the nuclear envelope, becomes a regular sphere, and gradually enlarges from a diameter of 0.4 μm in leptotene to 1.6 μm in diplotene. Concurrently, lacunae appear within its substance and enlarge. At each maturation division, the amount of round‐body material is decreased by about half, presumably because the constituent proteins are dissociated at metaphase, distributed between the two daughter cells at telophase, and reconstituted into half‐sized round bodies. As spermiogenesis proceeds, the round body shrinks gradually and disappears at step 8.Soon after its appearance at leptotene, the round body becomes associated with and is surrounded by the pars granulosa of one of the nucleoli. Moreover, 3H‐uridine incorporation into nucleolar RNA is high as long as the size of the round body increases, but is low or absent when it decreases. It is possible, therefore, that the round body exerts some control on nucleolar activity in meiotic cells.