bluuebunny/crossref_metadata_2025_split huggingface dataset:
Structure of oxyntic cell membranes during conditions of rest and secretion of HCl as revealed by freeze‐fracture
Authors: Black Joel A. , Forte Trudy M. , Forte John G. 
Published: February 2005

AbstractThe density and distribution of membrane associated particles of piglet oxyntic cell tubulovesicular and apical surface membranes were investigated during resting (nonsecreting) and secreting conditions. For the resting oxyntic cell, the abundant tubulovesicles showed a highly asymmetrical distribution of particles between fracture faces, with the P face heavily studded by particles and the E face particle deficient. The apical surface, however, had a relatively symmetrical distribution of particles on both membrane fracture faces. In contrast to the resting state, the apical surface of the stimulated oxyntic cell showed a marked asymmetry of membrane particles; the P face had a high density of particles, while there was a scarcity of particles on the E face. The observed changes in apical surface membrane particle distribution support the hypothesis that, following the initiation of acid secretion, the tubulovesicles fuse with and become an integral part of the apical surface. Thus, the apical membrane P face of the stimulated cell is enriched and the E face is diluted by the incorporation of tubulovesicular membranes.
Cell interactions between hematopoietic and stromal cells in the embryonic chick bone marrow
Authors: MiChael Sorrell J. , Weiss Leon 
Published: February 2005

AbstractLight microscopic, scanning electron microscopic, and transmission electron microscopic studies of the early developmental stages of chick embryonic bone marrow disclose characteristic associations of the first hematopoietic cells with stromal cells. The first hematopoietic cells, large basophilic cells that we have termed presumptive stem cells, segregate into erythropoietic and granulopoietic regions. Intravascular erythropoietic cells associate with sinusoidal endothelial cells, while granulopoietic cells associate with extravascular reticular cells. Extensive, intimate contacts between erythroid and endothelial cells are maintained, in part, by marginal arrays of microtubules, which promote a flattening of the adherent erythroid cell surface. In addition, cell surface components of opposing cells, visualized by ruthenium red staining, appear to merge and possibly to interact. Granulopoietic cells establish intimate but less extensive associations with reticular cells through cell‐surface interactions. Stationary granuloid cells appear to be held in place by small, thin processes emanating from the sheet‐like reticular cells. Granuloid cells are capable of moving within the extravascular region, using reticular cell surfaces as a substrate. Intimate associations also occur among granulopoietic cells, the significance of which is unclear. Thus, sinusoidal endothelial cells and reticular cells comprise the critical non‐hematopoietic or stromal elements of avian bone marrow, where they have a putative role in segregating presumptive stem cells into erythrocytic and granulocytic compartments. They serve as an architectual, and possibly regulatory, framework on which hematopoiesis occurs.
The ultrastructural histochemistry and stereoscanning electron microscopy of the rodent and amphibian surfactant systems
Authors: Stratton C. J. , Wetzstein H. Y. , Hardy T. 
Published: February 2005

AbstractUltrastructural histochemical procedures were employed to determine the carbohydrate components and their contributions to the rodent and amphibian surfactant systems. Zirconium stained the rodent (rat) cytoplasm surrounding the multilamellar bodies, the Golgi, and was associated with the membrane structures of the compact lamellae of alveolar multilamellar bodies. In the rodent and amphibian (Rana pipiens), ruthenium red stain was observed within all tubular myelin surfactant matricies. The “gutters” tubular myelin surfactant matrix, and intratubular myelin surfactant matrix materials all demonstrated a positive reaction product. The periodic acid‐chromic acid‐silver procedure revealed irregular channels extending from the multilamellar bodies to the surface of the rodent great alveolar pneumocyte.The extra‐pulmonary and respiratory surfaces in both species were additionally studied by stereoscanning electron microscopy. The respiratory anatomy of the rodent was corroborated. The amphibian lung demonstrated three orders of septa, and in the expired state, tertiary septal pits. The amphibian primary septa were hollow, blind tubules containing respiratory surfaces.
Structure and orientation of extracellular matrix in developing chick optic tectum
Authors: Krayanek Susan 
Published: February 2005

AbstractThe mechanisms underlying directed axonal movement in the developing central nervous system are largely unknown. Histochemical methods for transmission and scanning electron microscopy were used to study the surface of the developing optic tectum in the chick embryo at the time of optic fiber ingrowth.A highly structured extracellular matrix consisting of fibrillar and granular components was seen in normal and in uninnervated specimens that had been fixed in solutions containing the cationic dyes Alcian blue, ruthenium red, or safranin O. The strong affinity of these stains for glycosaminoglycans suggests that the matrix contains such macromolecular aggregates. With routine fixation methods the matrix was not seen, but empty extracellular spaces were apparent.The tectal matrix was particularly prominent ahead of the growing front of optic fibers. Its location was thus appropriate for interacting with pioneering axons that cross the surface of the developing tectum along its anteriorposterior axis. Matrix fibrils were organized in a stacked alignment predominantly parallel to the tectal surface, but otherwise their orientation appeared random. The matrix possibly bears on the guidance of optic fibers. However, its geometry suggests that this may involve a mechanism more specific than mechanical contact guidance.
A random arrangement of albumin‐containing hepatocytes seen with histo‐immunologic methods. II. Conditions that produce the artifact
Authors: Lebouton A. V. , Peters Masse J. 
Published: February 2005

AbstractThe cellular immunolocalization of albumin in rat liver has been studied as a function of various physiological and physical conditions. Our observations show that the prime requisite for accurate immunolocalization of albumin and other hepatic‐based proteins is the complete removal of blood and especially plasma from sinusoids and the perisinusoidal space of Disse prior to fixation.Fixation of blood‐filled liver specimens results in the antifactual entrance of plasma constituents into hepatocytes. When the fixative used is formaldehyde, the artifactual uptake occurs primarily into hepatocytes that have a high glycogen content. Fixation of blood‐filled liver with acetic acid‐ethanol causes a massive influx of plasma into all hepatocytes. On the contrary, with blood‐free liver, varying the type of fixative consistently demonstrates that all hepatocytes normally contain albumin, transferrin, and fibrinogen simultaneously.Increasing the time between cessation of blood flow and outright fixation by either withholding the fixative or by impeding its diffusion through the specimen causes a progressive loss of antigenicity of albumin. The same result ensues when specimens remain in contact with the fixative for an extended time.
Amplitude‐reduction and acrophase‐advance of circadian mitotic rhythm in corneal epithelium of mice with bilaterally lesioned suprachiasmatic nuclei
Authors: Powell E. W. , Pasley J. N. , Scheving L. E. , Halberg Franz 
Published: February 2005

AbstractLesions of the suprachiasmatic nuclei (SCN) have been reported to disrupt or abolish circadian rhythms of motor activity and body temperature as well as of several neuroendocrine functions. This study was undertaken to determine any effect the SCN may have on the prominent circadian rhythm characteristic of the mitotic index of the corneal epithelium. Singly caged adult mice of both sexes were fed ad libitum and standardized to 12 hours of light alternating with 12 hours of darkness. Animals were divided into experimental and control groups. Later they were killed in subgroups at the time intervals of 0800, 1200, 1000, 0000, 0400 hour. Mitotic counts were determined on both right and left corneas of all mice. The data were plotted separately for both groups and reflect colony variation. We conclude that major lesioning of the SCN or its efferent projections disturbed but did not abolish the rhythm. In animals with unilateral lesions of the SCN, the mitotic index was consistently lower in the ipsilateral cornea. The mitotic index for animals with lesions which missed the SCN or its efferent projections did not differ from controls. The nuclei appear to function as pace‐resetters and amplifiers of the rhythm studied.
Cyclic variations in the oviductal ciliated cells during the menstrual cycle and after estrogen treatment in the pig‐tailed monkey, Macaca nemestrina
Authors: Odor D. Louise , Gaddum‐Rosse Penelope , Rumery Ruth E. , Blandau Richard J. 
Published: February 2005

AbstractThe epithelium of the oviduct of the pig‐tailed monkey, Macaca nemestrina was studied (1) to determine whether quantitative changes in the number of ciliated, deciliated, reciliating and nonciliated cells occur during the menstrual cycle and under certain experimental conditions and (2) to describe the ultrastructure of the ciliated and ciliogenic cells. The mean percentage of ciliated cells decreased from 48.2 in the fimbriae and 48.3 in the ampullae in the postovulatory stage to 7.7 and 18.8, respectively in the late luteal phase; these changes are significant as determined by Duncan's multiple range test. In the early follicular phase 3.9% of the cells in the fimbriae and 11.2% in the ampullae are ciliated, and the number of ciliogenic (deciliated and reciliating) cells is the highest of any time in the cycle in both the fimbrial (6.3%)and ampullar (8.4%)epithelium. In contrast, although the percentage of ciliated cells in the isthmus varies from 44.4 in the preovulatory phase to 34.3 in the early follicular phase, the differences between the various times in the cycle are not significant. However, in the late luteal phase, the values for the fimbriae and ampullae are significantly different from that of the isthmi. Ciliated cells constitute less than 1% of both the fimbrial and ampullar epithelium 2 ¾ years after ovariectomy, but 16.7 in the isthmic tissue. In ovariectomized monkeys treated for 7 or 12 days with estradiol benzoate reciliation occurs, but to a significantly lesser extent in the fimbriae and ampullae than in the pre‐ or postovulatory animals; the degree of reciliation in the isthmus is not different from the values noted during the cycle. The ultrastructure of ciliated, deciliated and reciliating cells is described. Of much interest is the finding of cytoplasmic protrusions containing variable numbers of ciliary axonemal complexes. It is postulated that such internalization of ciliary micotubules may represent one way in which deciliation may be accomplished.
Phenobarbital‐induced alterations of the rat adrenal cortex
Authors: Penney David P. , Averill Kathy T. 
Published: February 2005

AbstractTo determine the morpholic changes in adrenocortices induced by chronic phenobarbital therapy, the male rats were orally administered the drug daily for varying periods up to three months. Fine structural changes attributable to the drug included mitochondrial pleomorphism and cavitation, loss of cholesterol ester clefts, reorganization of intracellular lipid, hypertrophy of the agranular endoplasmic reticulum and a juxtapositioning of the agranular endoplasmic reticulum, mitochondria and lipid droplets—all suggestive of an actively secreting cortex. The digitonin‐glutaraldehyde reaction suggested an active translocation of free cholesterol from lipid droplets to the mitochondria and agranular endoplasmic reticulum following phenobarbital treatment. Phenobarbital appears to stimulate corticosteroidogenesis due in large part to enhanced hepatic corticoid metabolizing enzymes.
Ultrastructure of the chondrocytes and extracellular matrix of the Swarm rat chondrosarcoma
Authors: Hascall Gretchen K. 
Published: February 2005

AbstractThe Swarm chondrosarcoma, a transplantable tumor maintained in rats, has a structure similar to hyaline cartilage. The extracellular matrix contains narrow, banded collagen fibrils and proteoglycan matrix granules. The cells are filled with organelles typically involved in synthesis and secretion, including an extensive rough endoplasmic reticulum with dilated cisternae, a large Golgi apparatus dispersed throughout the cell, and secretory vacuoles which fill directly from Golgi saccules. There is only one class of secretory vacuoles, suggesting that the secretory products, collagen and proteoglycan, are packaged and secreted together. The cells also contain unusual endoplasmic reticulum, many coated vesicles and multivesicular bodies, and abnormal mitochondria. The large amount of tissue available from the tumor, and its characterization biochemically (Choi et al., '71; Oegema et al., '75) and morphologically as cartilage, make the tumor valuable as a model tissue for studies of synthesis and secretion of extracellular matrix materials.
Distribution of iron in the gastrointestinal tract of the common vampire bat: Evidence for macrophage‐linked iron clearance
Authors: Morton David , Wimsatt William A. 
Published: February 2005

AbstractIron in the tissues of the digestive tract of the common vampire bat (Desmodus rotundus) has been studied using histochemical, electron microscopic, and autoradiographic methods. This animal is an obligate sanguivore and has a daily intake of dietary iron 800 times that of man. The amount and distribution of tissue iron is not affected by either a single blood meal or starvation but does reflect the degree of siderosis of each animal's liver and spleen. By 7 days after the injection of a trace amount of 55Fe into the peritoneal cavity, labelled siderotic macrophages are present both on the serosa and within the walls of the stomach and intestine. In the lower intestine, such cells can be derived from the germinal centers of Peyer's patches. Siderotic macrophages are often situated in the lamina propria under areas of siderotic epithelium. Label is also present in the apical cytoplasm of mucosal epithelial cells, a region of abundant siderosomes. The ultrastructure of these organelles is extremely variable. Accumulations of membranous whorls and stacks, “stippled bodies,” ferritin molecules, and larger “ferruginous” complexes are bounded by one or a number of membranes. Iron is excreted when these epithelial cells are desquamated into the gut lumen. Similar Prussian blue‐positive granules are present in the feces. Unlike other glandular cells, the parietal cells of the fundic caecum are siderotic. Their cytoplasm contains abundant siderosomes and ferritin with accumulations of amembranous ferritin bodies in the intracellular canalicular spaces. Prussian blue‐positive granules are present in the lumens of fundic glands.
Effects of orchidectomy on the adrenal macrophage system
Authors: Maglhães Manuel M. , Magalhães Maria C. 
Published: February 2005

AbstractMacrophages of the adrenal cortex were studied in normal and orchidectomized rats. In normal rats, few macrophages with numerous cytoplasmic granules were observed, mainly in the zona reticularis. Granules were limited by a single membrane and contained either a finely granular dense matrix or heterogeneous materials made up of electron‐lucent parts, dark granular and membranous areas. An aminotriazole‐resistant peroxidatic activity was confined to the dense granules. In orchidectomized rats, the number of macrophages was markedly increased, and the cells were concentrated at the border between the zonae fasciculata and reticularis and disseminated throughout the zona reticularis. Lysosomes were more numerous in each macrophage, and those of heterogeneous matrix were larger and their contents were more complex than in normal rats. These results show that orchidectomy stimulates the adrenal macrophage system.
Differential changes in cartilage cell proliferation and cell density in the rat craniofacial complex during secondary palate development
Authors: Diewert Virginia M. 
Published: February 2005

AbstractDuring mammalian secondary palate formation sagittal growth of the lower face has been shown to be more rapid than that of the upper face, and the tongue and mandible extend beneath the primary palate. In order to identify factors contributing to this differential growth pattern, cellular and morphologic growth of the major cartilages of the upper and lower facial regions were studied in radioautographic sections labeled with tritiated thymidine. Evaluation of cell‐density recordings, labeling indices, and structural dimensions revealed significant differences between Meckel's cartilage in the lower face, and the nasal cartilage and anterior cranial base cartilage in the upper face. After formation of the precartilaginous blastema, labeling indices were high in Meckel's cartilage (20–30%), but very low in the nasal cartilage and the anterior cranial base (0–2%). During secondary palate formation of the volume of Meckel's cartilage increased more rapidly than the other cartilages and its growth was primarily in the sagittal direction. Between days 15 and 17, the increase in the length of Meckel's cartilage (165%) was approximately twice as great as the increase in the combined length of the nasal cartilage and the anterior cranial base (77%). During this period induction of cleft palate with some teratogens has been shown to severely retard growth of Meckel's cartilage and produce mandibular retrognathia that contributes to delayed elevation of the palatal shelves. Therefore, extensive cell proliferation in Meckel's cartilage, during a period of limited proliferation in other craniofacial cartilages, appears to contribute to its rapid growth and its differential sensitivity to growth inhibition.
Secondary palatal development in the New Zealand white rabbit: A scanning electron microscopic study
Authors: Meller Samuel M. , De Paola Dominick P. , Barton Lorraine H. , Mandella Rosemary D. 
Published: February 2005

AbstractExamination of surface topography in prefusion stages of secondary palatal development in rabbit embryos reveals a sequence of alterations in the surface cells of the epithelium along the medial margins of the palatal processes. A progressive increase in cellular protrusions resembling lamellipodia and filopodia, as well as cellular necrosis, is observed in those areas that undergo fusion. The changes precede fusion and are restricted to fusion sites. Prior to and at the time of epithelial contact between palatal processes, many long slender cellular protrusions are seen bridging the gap between the approximating tissues. The localization of the epithelial alterations and the appearance of similar cellular morphology in other embryonic epithelial fusion events strongly suggest: either an active role of the epithelial cells in the fusion of the secondary palate, or some common fundamental biochemical events that may facilitate or are responsible for the initial adhesion of such tissues.
Intramembrane events accompanying junction formation in a liver cell line
Authors: Montesano Roberto 
Published: February 2005

AbstractTo study intramembrane events leading to the establishment of intercellular junctions between epithelial cells in vitro, we examined monolayer cultures of a rat liver cell line by an in situ freeze‐fracturing technique (Pauli et al., J. Cell Biol., 72:763, 1977). Our observations indicate that an early step of junction formation between liver cells consists of the differentiation of a particle‐poor membrane stretch showing a honeycomb pattern of shallow P‐face depressions or E‐face bulges (“formation band”). This change in membrane organization precedes and accompanies the subsequent aggregation of junctional particles. The latter process results in the formation of irregular particle islands with peripheral branchings which tend to encompass the depressions in the membrane. The linear branchings grow and interconnect in a network of beaded strands, which gradually transform into smooth tight junctional fibrils, as previously described in fetal liver in vivo (Montesano et al., J. Cell Biol., 67:310, 1975), while the particle islands assume the typical configuration of mature gap junctions. Formation bands are particularly prominent between liver cells grown in the presence of hydrocortisone (5 μg/ml) in the culture medium.
Microtubule and microfilament populations of cell processes in the dental pulp
Authors: Holland G. R. 
Published: February 2005

AbstractAn attempt has been made to characterize the nature of the unidentified cell processes participating in gap junctions in the odontoblast layer. In peripheral and pulpal nerves, there is a strong relationship between axon caliber and microfilament and microtubule populations. This characteristic, together with the ratio of microtubules to microfilaments, has been measured and compared for four types of cell processes found in the dental pulp, including those participating in gap junctions. The processes taking part in the gap junctions cannot be distinguished from pulpal axons on the basis of microtubule‐to‐microfilament ratio nor on the relationship between microtubule and microfilament population and process caliber. While these findings do not prove that the “gap members” are nerve fibers, it does support the hypothesis that the processes taking part in gap junctions in the peripheral dental pulp are nerve fibers.
The renal cortical lymphatic system in dogs with unimpeded lymph and urine flow
Authors: O'Morchoe Charles C. C. , Albertine Kurt H. 
Published: February 2005

AbstractThe distribution and extent of the lymphatic circulation in the renal cortex was analyzed in three dogs under conditions of unimpeded lymph and urine flow. The kidneys were drip fixed with acrolein in vivo, and cortical tissue strips were prepared for light and electron microscopic examination. Analysis of 90 tissue strips revealed 38 cortical lymphatics, one third of which were intralobular in position. The intralobular lymphatic capillaries were related primarily to tubules, afferent arterioles, or renal corpuscles. The remainder of the lymphatics were located in interlobular connective tissue areas in association with the interlobular blood vessels. Interlobular lymphatics had a surface area twice that of intralobular vessels. Stereological analysis was used to estimate the volume density of the components of the renal cortex. The volume density of lymphatics was found to be 0.0014, but because of the relative infrequency of lymphatics, this value was considered to be approximate. The volume density data for non‐lymphatic renal components were found to be in close agreement with published data. From these volume density values it was concluded that the volume of cortical lymph in a functioning dog kidney is equivalent to about 1% of the volume of blood in the cortical peritubular capillaries.