bluuebunny/crossref_metadata_2025_split huggingface dataset:
Circadian variation in cell division of the mouse alimentary tract, bone marrow and corneal epithelium
Authors: Scheving Lawrence E. , Burns E. Robert , Pauly John E. , Tsai Tien‐Hu 
Published: February 2005

AbstractCircadian rhythms in DNA synthesis are described for the tongue epithelium, five different regions of the alimentary canal (gut) –esophagus, stomach, duodenum, jejunum and rectum– and bone marrow in a group of BDF1 male mice. A circadian rhythm is also described for the mitotic index in the corneal epithelium in the same mice. The data document for the first time in the same animals the dramatic variation in cell division encountered from one region of the gut to another. This variation is seen in the amplitudes of the rhythms as well as in the over‐all 24‐hour means. On the contrary, the phasings of the rhythms in the different regions of the gut are remarkably similar. In this study, where the mice were standardized to 12 hours of light (0600‐1800) alternating with 12 hours of darkness, the peak of the DNA‐synthesis rhythm occurred around the time of transition from dark to light, and the trough around the time of transition from light to dark. The implications of these findings, and those of others, to the study of cell kinetics and to cancer chemotherapy are discussed.
The merkel cell in the labial ridge epidermis of anuran tadpole. I. Fine structure, distribution and cytochemical studies
Authors: Tachibana Tamiko 
Published: February 2005

AbstractThe labial ridge epidermis of the anuran tadpole, which is the formative site of horny teeth, was studied with the electron microscope. The triangular epidermis covering the apex of the labial ridge was composed of horny teeth cells arranged in a columnar shape, keratinocytes, secretory epidermal cells, two kinds of non‐epidermal cells and Merkel cells. Individual non‐epider‐mal cells were identified as neutrophils and macrophages respectively.In addition, the fine structure, distribution and cytochemistry of the Merkel cell were studied. The fine structure of Merkel cells in the labial ridge epidermis was not so different from those of other vertebrates reported previously by other workers, except for the presence of numerous glycogen particles. The presence of Merkel cells in the labial ridge epidermis was very frequent, and they were arranged in a line at a uniform level of the triangular epidermis. They were usually located in the third cell layer from the base of the epidermis.PAS and azure A stains were used on semithin epoxy sections to reveal the Merkel cells, and both stained them intensely. On the other hand, though glutaraldehyde‐silver techniques and permanganate fixation were used to detect monoamines in the Merkel cells ultracytochemically, a positive reaction was observed on the pigment granules.
Regional differentiation of cell junctions in the excurrent duct epithelium of the rat testis as revealed by freeze‐fracture
Authors: Suzuki Fumie , Nagano Toshio 
Published: February 2005

AbstractIntercellular junctions of the excurrent duct system of the adult rat testis were studied by freeze‐fracture. In the terminal segment of the seminiferous tubule, where there are no spermatogenic cells, the tight junctions of Sertoli cells consist of many parallel strands of particles. The particles of the junctions predominantly appear on the E face instead of the P face, similar to those of the seminiferous tubules reported previously. From the rete testis to the ductus deferens, the tight junctional particles or smooth strands are mainly found on the P face, and the tight junctions show anastomosing networks. In the ductuli efferentes, whose epithelial lining consists of ciliated and nonciliated cells, the tight junctions between two adjacent nonciliated cells and between nonciliated and ciliated cells are poorly developed. In the former, belt‐like gap junctions are often associated with segmented tight junctions. In such area, there are tiny regions, where no junctional elements are observed. Between two ciliated cells, several strands of the tight junctions can be seen. The result of the tracer experiment suggests that the barrier of the ductuli efferentes is weak. In the epididymis, the tight junctions are well developed throughout the duct. Corresponding with the regional variation of the epi‐didymal epithelium, the geometrical organization of the tight junction networks varies along the duct. In the ductus deferens, many strands of the tight junctions are scattered throughout the lateral cell surface in addition to the belt‐like network of the tight junction in the adluminal area.The number of the tight junctional strands is presented graphically in the various segments of the excurrent duct of the testis.
Morphological observations on the normal human cardiac glands
Authors: Krause William J. , Ivey Kevin J. , Baskin William N. , Mackercher Peter A. 
Published: February 2005

AbstractThe majority of human cardiac glands that lie immediately distal to the termination of esophageal epithelium are compound or branched tubular glands. They empty into overlying gastric pits. The glands of this region are often organized into lobule‐like complexes by the surrounding connective tissue of the lamina propria. The secretory tubules contain mucous cells, parie‐tal cells and endocrine cells. The mucous cell is the most common cell type observed and appears to comprise two populations. The majority are pyramidal in shape and show numerous spherical, electron‐dense secretory granules. Profiles of rough endoplasmic reticulum are observed scattered throughout the cytoplasm and Golgi complexes occupy a supranuclear position in relation to forming secretory granules. Morphologically this cell type appears similar to the mucous neck cell of the fundus. Secretory granules of a second mucous cell type are mottled in appearance and show an area of increased electron density near the limiting membrane. Parietal cells are observed and appear identical to those in the fundus. The large number of endocrine cells present raises questions concerning the traditional concept of the function of these particular glands.
Alterations in hepatic fine structure after chronic exposure of rats to dexamethasone
Authors: Garfield Sanford A. , Scott Alexis C. , Cardell Robert R. 
Published: February 2005

AbstractThe objective of this study was to determine the effects of chronic dexamethasone (DEX) administration on hepatic ultrastructure and to correlate these changes with plasma lipoprotein levels. Electron microscopic studies were made of hepatocytes from male rats killed 1, 3 and 5 days after DEX (2 mg, twice per day) administration. Three days after treatment plasma lipoprotein levels were highest and hepatocytes contained regions of the cytosome rich in elements of the smooth endoplasmic reticulum (SER). Osmiophilic particles were present in the tubules and vesicles of the SER, in the saccules and vacuoles of the Golgi complex, in secretory vesicles near the cell surface and in the space of Disse. DEX treatments also caused hepatocytes to accumulate tightly packed masses of β‐particles of glycogen in some regions of the cell while other areas displayed dispersed glycogen particles that were associated with the SER. These observations are consistent with the hypothesis that glucocorticoids 1. cause an elevation of plasma lipoprotein levels by in creasing hepatic synthesis and secretion of VLDL, which involves the sequential participation of the ER, the Golgi complex and exocytosis of VLDL‐containing vacuoles into the space of Disse, and 2. produce a change in the nature of the association of glycogen particles with the SER membranes in response to the physiological state of the animal.
Rod‐shaped particles in the plasma membrane of the mitochondria‐rich cell of amphibian epidermis
Authors: Brown D. , Ilic V. , Orci L. 
Published: February 2005

AbstractA freeze‐fracture study has revealed rod‐shaped intramembra‐nous particles on the plasma membrane P‐face (cytoplasmic leaflet) of the mi‐tochondria‐rich cell (or flask cell) of Xenopus laevis and Rana ridibunda epidermis. Such particles have previously been found in all other mitochondria rich cells examined by this technique, namely, the MR‐cell of toad bladder epi‐thelium, the dark cèll of rat kidney collecting tubule, and the flask cell of Xenopus kidney collecting tubule. These particles are assumed, therefore, to be closely connected with the function of this cell type.
A quantitative analysis of hepatic ultrastructure in rats during enhanced bile secretion
Authors: Jones Albert L. , Schmucker Douglas L. , Mooney Jill S. , Adler Ronald D. , Ockner Robert K. 
Published: February 2005

AbstractThe ultrastructural changes in hepatocytes of rats subjected to selective biliary obstruction (SBO), wherein the biliary system draining approximately two‐thirds of the liver is obstructed, were evaluated by quantitative electron microscopy or stereology. The remaining unobstructed portion of the organ compensates for this loss of bile secretion by functioning in a hyper‐secretory mode. This animal model permits the comparison of hepatocellular fine structure associated with the conditions of nonsecretion and hypersecre‐tion of bile with that found in normal secreting sham‐operated rats. Since recent evidence suggests the presence of lobular gradients in hepatic structure and function, both centrolobular and periportal hepatocytes were examined. The low incidence of Golgi membrane profiles in high magnification electron micrographs results in a low confidence level of sampling and, thus, necessitates the application of a novel parameter for estimating the amount of Golgi complex, i.e., the Golgi‐rich area.For the most part, the lobular variation in hepatic fine structure in the sham‐operated animals was similar to that described by Loud ('68). However, the periportal parenchyma contained approximately twice the volume of Golgi‐rich area as the centrolobular tissue. The amount of cytoplasmic lipid increased significantly in the SBO unobstructed lobes, although there were few or no changes in the other intracellular organelles or inclusions except those related to the Golgi complex. The volume of Golgi‐rich area increased significantly in the centrolobular tissue of the SBO unobstructed (hypersecretory) lobes to the extent that both intralobular zones contained similar amounts of this component. These data suggest that the Golgi complex is a dynamic unit which responds to changes in hepatocellular activity and may be involved in bile secretion.
Orthogonal arrays of particles in plasma membranes of the gastric parietal cell
Authors: Bordi Cesare , Perrelet Alain 
Published: February 2005

AbstractFreeze‐fracture of rat gastric mucosa revealed a specific set of intramembranous particles in the plasma membrane of the parietal cells. The particles were small and of square shape and formed orthogonal arrays in the P‐face with corresponding orthogonal arrays of pits in the E‐face. Arrays, scattered among usual globular particles, were particularly numerous at the basal pole of the cell and less concentrated on the lateral side. They were not present in the apical microvillar membrane nor in the membranes of intracellular tubulovesicles. As in other cell types in which similar arrays were described previously (e.g., astrocytes, “light” cells of the kidney collecting tubule), their presence in parietal cell membranes suggest some specialized function of these membranes not shared by plasma membranes showing only a population of globular particles. This function has yet to be identified.
Ultrastructure of developing alveoli. I. The role of the interstitial fibroblast
Authors: Vaccaro Charles , Brody Jerome S. 
Published: February 2005

AbstractWe examined the ultrastructural features of postnatal alveolar septal formation in rats from birth to 28 days of age. At birth, the rat lung consists of large saccules with thick walls and cellular interstitium. Interstitial cells have large oval nuclei with scant cytoplasm containing few organelles and scattered lipid droplets. These cells appear to be poorly differentiated mesenchymal cells not engaged in active protein synthesis or secretion. Between 5 and 15 days of age, saccule walls thin and many new alveolar septa form. Two types of interstitial fibroblasts are present: one which appears at the tips of newly formed septa has the characteristics of a myofibroblast and appears to be engaged in synthesis and secretion of elastin; the other fibroblast appears at the base of new septa, is filled with lipid and contains few other cytoplasmic organelles. After 15 days of age, alveolar walls become thinner, few new septa form and interstitial fibroblasts begin to resemble the dormant type of fibroblasts seen at birth. Thus, the process of postnatal alveolarization of lung parenchyma involves differentiation of the interstitial fibroblast and elastogenesis. The factors which control this process, the precise role of elastogenesis in alveolar septal formation, the origin and fate of the lipid filled fibroblast and the ultimate fate of the myofibroblast remain to be determined.
Morphological and quantitative analysis of spermatogonia in mouse testes using whole mounted seminiferous tubules. II. The irradiated testes
Authors: Huckins C. , Oakberg E. F. 
Published: February 2005

AbstractIn adult male mice exposed to 300 R X‐irradiation, the sper‐matogonial population was selectively killed except for the radioresistant type As stem cells. Type A spermatogonia were minimal two days after irradiation, when only 20% of the control population was present in stages 5‐6; these were predominately single and paired undifferentiated cells. When multiple injections of 3HTdR were given between 2 and 3.5 days post‐irradiation, 90–95% of these survivors in stages 4‐6 became labeled. Enhanced proliferation of these stem cells, and at times when they were normally quiescent, led to restoration of all classes of spermatogonia by 11 days after irradiation.Several autoradiographic studies were undertaken to better characterize the radioresistant cells. In mice given single or multiple injections of 3HTdR prior to irradiation, there was appreciable retention of label by those type As sper‐matogonia that had originally incorporated 3HTdR in stages 2‐4. This labeling pattern was identical to that of the long‐cycling As stem cells in nonirradiated testes. Since the long‐cycling As stem cells are thought to be characterized by a prolonged G1 or “A‐phase” which is known to be a highly radioresistant portion of the cell cycle, it was clear why these cells could preferentially survive irradiation doses that killed other spermatogonial types. It was proposed that following germ cell depletion, as after irradiation injury, the long‐cycling As survivors could be prematurely triggered from A‐phase into DNA synthesis, thereby, initiating restoration of the germ cell population.
Ultrastructural cytochemistry of atrial muscle cells. VI. Comparative study of specific granules in right and left atrium of various animal species
Authors: Cantin Marc , Timm‐Kennedy Martina , El‐Khatib Ellen , Huet Madeleine , Yunge Lawrence 
Published: February 2005

AbstractSpecific (A‐, B‐ and D‐) granules as well as multivesicular bodies (MVB) with a dense core from the right and left atrium of a variety of mammals (mouse, rat, hamster, guinea pig, rabbit, young and old cat) were compared by quantitative ultrastructural and cytochemical methods as regards number, size, localization and reactivity. The number of specific granules was greater in the right atrium of the rat and lesser in the same atrium of the guinea pig. In the rat this difference was due to a greater number of all three types of specific granules in the right atrium. In the guinea pig, both A and B granules were more numerous in the left atrium. A greater number of granules was also found in the left atrium of hamster, rabbit and young and old cat but the difference with the right atrium was not significant. All atria contained the same type of specific granules but A‐ and B‐granules were present in the left atrium not only in the paranuclear area, as in the right atrium, but also throughout the sarcoplasm. In both atria, all specific granules were argen‐taphobic when stained according to the periodic acid‐thiocarbohydrazide‐silver proteinate technique of Thiery. They reacted positively to phosphotungstic acid‐hydrochloric acid (PTA) (pH 0.3) as did the cell coat, residual bodies (Cgranules), lysosomes, Z‐disks and a small portion of the Golgi complex. The PTA and PAS stains were abolished by acetylation, restored by saponification, unchanged by methylation and greatly diminished by sulfation. The MVB with a dense core, identical to those already noted in the cells of various endocrine glands, and thought to be crinophagic, were rare in the right atrium of all species and absent in that of the rat. They were much more numerous in the left atrium, particularly of hamsters, guinea pigs and cats and, to a lesser degree, of mice, rabbits and rats. They were silver negative. Their dense core reacted to PTA but their matrix, contrary to classical MVB without a dense core, did not.
Histological and ultrastructural observations of tail bud formation in the chick embryo
Authors: Schoenwolf Gary C. 
Published: February 2005

AbstractTail bud formation was studied in chick embryos by light and electron microscopy. The caudal part of the neural groove at stage 11 is flanked by widely separated neural folds and merges posteriorly with the shallow primitive groove. The neural groove and primitive streak partially overlap. The depth of the neural groove gradually decreases antero‐posteriorly within this overlap zone while the dorso‐ventral thickness of the streak progressively increases. The anterior end of the streak begins to form a spherical accumulation of mesenchymal cells, the incipient tail bud, concomitant with closure of the posterior neuropore. Formation of the posterior body fold results in consolidation of the remainder of the streak into the definitive tail bud. The overlap zone between neural groove and primitive streak is retained as the tail bud forms. Thus the posterior end of the neural tube and anterior end of the tail bud overlap. The latter undergoes cavitation to form the ventral part of the spinal cord within this overlap region.The tail bud is initially continuous with an overlying, flattened layer of ectoderm and an underlying, columnar layer of endoderm. A bilaminar ectodermal epithelium forms directly above the developing neural tube as the dorsal portion of the tail bud undergoes cavitation. Most of the endodermal cells are displaced from the ventral surface of the tail bud by the posterior body fold and condensed into a disk‐shaped region which ultimately gives rise to tail gut.
Renal regeneration following D‐serine induced acute tubular necrosis
Authors: Peterson Darryl R. , Carone Frank A. 
Published: February 2005

AbstractRegeneration of the rat kidney was observed for six days after inducing acute tubular necrosis of the proximal pars recta with d‐serine (80 mg/100g body weight). Regenerating cells appear by two days post‐treatment, and re‐epithelialization of the nephron is completed within six days, with the most mature cells approaching normal morphology. Regeneration originates from viable cells adjacent to the necrotic zone which divide and follow a template provided by the intact basement membrane. Transient, cytoplasmic regenerative activity among developing tubular cells is characterized by the presence of large, irregularly shaped nuclei, prominent nucleoli, abundant ribosomes and lysosomes, and abnormal mitochondrial configurations. Microfilaments appear to be involved in the formation of apical microvilli and the basal labyrinth of plasmalemmal convolutions. These data suggest that d‐serine. inducedacute tubular necrosis of the proximal pars recta may be followed by rapid, patterned regeneration along an intact basement membrane, and that microfilaments are involved in differentiation of cellular morphology.
The effect of dichloromethylene diphosphonate, a pyrophosphate analog, on bone and bone cell structure in the growing rat
Authors: Miller Scott C. , Jee Webster S. S. 
Published: February 2005

AbstractDichloromethylene diphosphonate (Cl2MDP) is a synthetic compound related in structure to inorganic pyrophosphate but is resistant to enzymatic and chemical degradation and is known to be a potent inhibitor of bone resorption. The administration of 20 mg/kg/day of Cl2MDP for ten days to growing rats results in marked increases in metaphyseal mineralized tissue mass due to slowed bone resorption. There was an increase in resorption areas covering anorganic bone viewed by scanning electron microscopy (SEM), however, the resorption pits, or Howship's lacunae, in these resorption areas were smaller and less defined than those encountered in controls. The appearance of these large areas of poorly delineated resorption pits is likely due to an inhibition of bone resorption coupled with slowed bone formation. Administration of Cl2MDP to growing rats also results in an increase in the numbers and size of osteoclasts. Because this would appear to be a histological paradox, in view of the ability of Cl2MDP to slow bone resorption, the osteoclasts were examined by transmission electron microscopy (TEM). The ruffled borders and associated cytoplasmic vacuoles were generally less extensive in the Cl2MDP‐treated osteoclasts than in controls, even though clear zones were frequently seen. Examination of undecalcified light microscope sections reveal that the area of bone being degraded by adjacent osteoclasts was generally much smaller in the Cl2MDP‐treated animals than in controls. Thus the collaborating TEM observations of smaller ruffled borders, with the SEM observations of smaller, less‐de‐fined resorption pits, with the light microscope observations of smaller bone areas being degraded by individual osteoclasts provide a morphological basis for the observed decreases in bone resorption following Cl2MDP administration.
Development of the intrarenal vascular system of the puppy kidney
Authors: Evan Andrew P. , Stoeckel James A. , Loemker Vickie , Baker Jeffrey T. 
Published: February 2005

AbstractThis study investigates the development of the vascular system of the puppy kidney (1‐21 days after birth) after preparing casts of the renal vessels. At two days, the intrarenal vascular system distal to the afferent arteriole is strikingly different than that of the adult. The glomeruli of the outer cortex consist of a single dilated vessel while those of the mid and inner cortex possess an increasingly larger number of capillary loops. The efferent arterioles vary greatly in appearance from outer to inner cortex. Those in the nephrogenic zone are characteristically short and narrow and join a larger venous vessel termined a sinusoidal capillary. An efferent system somewhat similar to that of the adult is seen in the mid and inner cortex. One of the most obvious differences noted between the puppy and adult kidney is the relative lack of peritubular capillary networks throughout the cortex of the puppy kidney. The puppy possesses large, irregular vessels termed sinusoidal capillaries. The most rudimentary sinusoids are found in the outer cortex with more mature vessels in the inner cortex. The vascular arrangement of the efferent arteriole and sinusoidal capillary appears as a post‐glomerular shunt. Functionally, the shunt would direct blood flow away from the proximal tubule and thus could result in a low extraction ratio and Tm for secreted solutes.