bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fine structural peculiarities of the pectoral fin dermoskeleton of two Brachiopterygii, Polypterus senegalus and Calamoichthys calabaricus (Pisces, Osteichthyes)
Authors: Géraudie Jacqueline 
Published: February 2005

AbstractThe features of the dermal skeleton of the pectoral fins of two Brachiopterygii, Polyterus senegalus and Calamoichthys calabaricus, have been studied by light and electrom microscopy. The components studied are the ganoine covered lepidotrichia segments and the distally located actinotrichia, the features of which are similar to those in teleosts. An irregular patch of ganoine susceptible to erosion by vascular canals lies on top of the cellular bone of the upper surface of the segment. It is separated from the stratified epidermis by an organic intermediate layer in place of the dermoepidermal interface. This layer is interpretated as “antislip pad” or elastic glue anchoring the epidermis on the hypermineralized ganoine. Such components are also observed in ganoid scales, although embryological data fail to support that lepidotrichial segments are modified scales. The lack of dentin in lepidotrichia emphasizes the tendency during evolution toward the reduction of some dermoskeletal components and exemplifies ganoine deposition directly on top of the bones as in holostei scale. The participation of neural crest cells in development of the dermal skeleton is discussed by way of the repartition of the odontods within the pectoral fin.
Distribution of esterase activity at the level of the epithelium of the diffusely infiltrated area (DIA) and of the cloaca in the Gallus domesticus: An ultrastructural study
Authors: Dolfi A. , Giannessi F. , Bianchi F. , Lupetti M. 
Published: February 2005

AbstractEsterase activity studies on the areas of lymphoid infiltration in the bursa of Fabricius (diffusely infiltrated area) and the dorsal wall of the cloaca showed that the epithelial cells exhibit varying degree of diffuse esterase activity; it was possible to demonstrate the presence of spot‐like esterase positivity in star‐shaped cells in the epithelium itself. These cells can be found at various levels from the proximal to the distal region and have also been observed in the connective tissue of the tunica propria; as a result, the hypothesis has been advanced that they are connective tissue.
Stochastio morphological model of the rat lung
Authors: Koblinger László , Hofmann Werner 
Published: February 2005

AbstractThe laboratory rat is often used as a human surrogate in aerosol inhalation studies. Here we present a new stochastic model for the rat lung analogous to that for the human lung. Morphometric data on the tracheobronchial geometry of the rat lung provided by the Lovelace Inhalation Toxicology Research Institute were analyzed. The results of this statistical analysis reveal significant differences in diameters and branching angles between major and minor daughter tubes starting from the same bifurcation. As a consequence of the more monopodial airway branching in the rat lung compared to the more dichotomous structure of the human lung, we recommend classifying the rat lung airways by their diameters and not by generation numbers. The distributions of the gemetric airway parameters and the correlations among them will be used for Monte Carlo deposition calculations.
Innervation and gap junction formation in the myometrium of pregnant little brown bats, Myotis lucifugus
Authors: Buchanan G. D. , Garfielde R. E. , Younglai E. V. 
Published: February 2005

AbstractPregant Myotis lucifugus were captured in mist nets set outside a large maternity colony and, in most cases, were examined 12–15 hours later. Anterior and posterior halves of uteri were pinned to dental wax and either incubated in glyoxylic acid to produce adrenergic nerve fluorescence, or fixed in buffered glutaraldehyde for electron microscopy. Blood was collected for radioimmunoassay of plasma progesterone. We found no evidence of decreased nerve fluorescence even in late pregancy when plasma progesterone levels were 10–20 times preovulatory values. Ultrastructtural examination also showed no evidence of damage to, or destruction of, nerves in the myometrium. However, we did find gap junctions between myometrial muscle cells during the periparturient period in both normal and aborting bats. Gap junctions began to form several days before term, increased in number until parturition, then decreased dramatically within a day or two thereafter. The percentage of muscle cell plasma membrane involved in gap junction formation was closely correlated with plasma progesterone levels, although whether this is causal or coincidental is not certain.These data do not agree with the conclusion drawn from observations in other mammals that a disappearance of adrenergic nerves from the myometrium is associated with the initiation of parturition, or that gap junction formation is associated with changes in nerve function. They do, however, lend further support to the hypothesis that there is neurogenic control of myometrial contractility in M. lucifugus, uteri at term.
Effects of mevinolin, an inhibitor of cholesterol synthesis, on the morphological and functional responses of rat adrenal zona fasciculata to a prolonged treatment with 4‐aminopyrazolo‐pyrimidine
Authors: Mazzocchi Giuseppina , Rebuffat Piera , Belloni Anna S. , Gottardo Giuseppe , Meneghelli Virgilio , Nussdorfer Gastone G. 
Published: February 2005

AbstractRat adrenocortical cells are almost completely dependent upon the continuous supply of cholesterol derived from serum lipoproteins. However, a prolonged (5‐day) administration of 4‐aminopyrazolo‐pyrimidine (4‐APP), a potent hypocholesterolaemic drug, though provoking a notable decrease in the intra‐adrenal concentration of esterified and free cholesterol, did not significantly affect basal plasma level of corticosterone. Morphometry showed a conspicuous hypertrophy of zona fasciculata cells, coupled with a striking proliferation of smooth endoplasmic reticulum (SER) and peroxisomes and with a profound lipid‐droplet depletion. The secretory response of zona fasciculata cells to ACTH was still present, but reduced by half with respect to control rats. The simultaneous administration of mevinolin, an inhibitor of cholesterol synthesis, to 4‐APP‐treated rats caused an additional drop in the intracellular content of free cholesterol and notably lowered basal plasma corticosterone concentration. Mevinolin magnified the 4‐APP‐induced zona fasciculata cell hypertrophy, as well as SER and peroxisome proliferation. The secretory response to ACTH was completely suppressed. These data are compatible with the view that the morphological changes, which rat zona fasciculata cells undergo during prolonged hypocholesterolaemia, are the expression of the activation of the endogenous cholesterol synthesis. This compensatory response, enabling zona fasciculata cells to maintain a normal basal rate of hormonal output and to respond (though less efficiently) to their main physiological stimulus, seems to be completely independent of any activation of the hypothalamo‐hyphophyseal axis, since dexamethasone/ACTH treated rats were used. The hypothesis is advanced that the mechanism underlying this response may involve the decrease of the intracellular free‐cholesterol pool.
In vivo homing of thymus‐enriched bone marrow cells
Authors: Klussmann Kurt G. , Haar Jack L. 
Published: February 2005

AbstractA population of adult CBA/J mouse bone marrow (BM) cells enriched by in vitro migration to supernatant prepared from neonatal thymus was labeled with a DNA‐binding fluorochrome, Hoecbst dye No. 33342 (H33342). Labeled cells were injected into irradiated recipients in order to compare the in vivo localization of the migration‐enriched BM (MEBM) cells to the localization of injected nonenriched BM (NEBM) cell controls. A characteristic difference in the distribution of localized cells was observed in the spleen but not in other lymphoid organs. At 2 hr after injection the MEBM cells were located in the marginal zones surrounding the periarterial lymphoid sheaths (PALS) of the splenic white pulp. At 6 hr after injection the MEBM cells were seen distributed between marginal zones and the PALS and by 16 hr they had localized almost exclusively in the white pulp. In contrast, the NEBM cells were located in the marginal zones or red pulp for the duration of the experiment. These observations show that the MEBM cells home selectively to T‐cell areas of the spleen. Direct immunofluorescent monoclonal antibody staining of H33342‐labeled cells obtained from the recipient spleens at 16 hr demonstrated that the MEBM cells were negative for Thy‐1 antigen, indicating that acquisition of Thy‐1 was not prerequisite to the observed homing. The results are compared to known localization patterns of mature lymphocytes.
Involvement of cathepsins B and H in lysosomal degradation of horseradish peroxidase endocytosed by the proximal tubule cells of the rat kidney: I. Histochemical and immunohistochemical studies
Authors: Yokota Sadaki , Kato Keitaro 
Published: February 2005

AbstractImmunohistochemical localizations of horseradish peroxidase (HRP) and cathepsins B and H in the lysosomal system of the rat kidney proximal tubule cells were investigated during the internalization and degradation of HRP by these cells. At fixed intervals after intravenous injection of HRP, the kidneys were fixed by perfusion. Five to fifteen minutes after this injection, endocytosed HRP was detected in fine granules beneath the brush border. Thirty minutes later, it accumulated into large aggregates of granules (phagosomes), where both enzymatic and antigenic activities appeared to cause HRP to be lost rapidly. After 1 hour, the aggregates of phagosomes increased in number and size but soon began to decrease gradually. In the early stage, cathepsins B and H were not detected in the apical cytoplasmic granules. However, they were present in the lysosomal compartments, together with the HRP. The large aggregates of phagosomes showed a patchy reaction, especially approximately 30 minutes after injection, whereas other medium‐sized phagosomes were stained heavily. Aggregates of phagosomes were present only in the S1 segment. These results suggest strongly that cathepsins B and H are involved in the cellular degradation of endocytosed HRP.
Development of Bone‐like substance in cartilaginous rat nasal septum under experimental conditions
Authors: Tsao S. W. , Chuah M. I. 
Published: February 2005

AbstractThe anterior part of the mammalian nasal septum (NS) persists throughout the life span as hyaline cartilage, in contrast to cartilage in most parts of the body, which is gradually replaced by bone during development. In this study, we have cultured differentiating rat NS under various experimental conditions in an attempt to gain some insight into the osteogenic potential, if any, of the NS and its surrounding connective tissue. Differentiating NS from E15 and E19 rat embryos were dissected and grown under the following conditions: 1) organ cultured in Waymouth's medium or modified Eagle's medium, with or without serum; 2) cultured on chick chorioallantoic membrane (CAM); 3) implanted under rat kidney capsule (KC). Bone‐like substance (BLS) never developed in organ cultures, but was observed in CAM cultures and KC implants after 7 days. The BLS was located external to the perichondrium of the NS and was stained red by the van Gieson's technique, indicating the presence of mature collagen. Further evidence of its bone‐like characteristics was demonstrated by the presence of alkaline phosphatase and type I collagen. The CAM and KC represent two experimental conditions under which progenitor cells in the nasal septum area may be induced to synthesize BLS.
Anatomical basis of a passive mechanism for ovum retention at the ampulloisthmic junction
Authors: Halbert Sheridan A. , Szal Sara E. , Broderson Stevan H. 
Published: February 2005

AbstractThe unexplained behavior of egg retention at the ampulloisthmic junction (AIJ) is a mechanical phenomenon; therefore the key to this process must lie in the anatomy of the oviduct. To investigate the concept that simple anatomical differences between ampulla and isthmus cause AIJ retention, we quantified, in these two regions of the rabbit oviduct, the structural characteristics of the tubal wall that show marked differences: wall thickness and luminal caliber. The oviductal wall greatly increases in thickness and decreases in luminal caliber abruptly at the transition from ampulla to isthmus. These passive mechanical factors predict a dramatically reduced distensibility of the isthmic wall compared to that of the ampulla, and these factors provide us with a simple model to account for the apparent sphincteric activity of the AIJ. Actual measurements of tubal distensibility confirmed our prediction. In addition, egg transport studies following microsurgical removal of the AIJ showed normal transport, an indication that no special structure need exist at the AIJ. We conclude that the contrasting morphology of the ampulla and isthmus may suffice to explain AIJ retention, and no special active mechanism need be postulated.
Changes in the distribution of microtubules in rat Sertoli cells during spermatogenesis
Authors: Vogl A. W. 
Published: February 2005

AbstractI have studied the distribution of microtubules in rat Sertoli cells during spermatogenesis. The distribution of microtubules was determined by indirect immunofluorescence in fragments seminiferous epithelium which were mechanically dissociated from perfusion‐fixed tests. The presence of microtubules in regions indicated by immunofluorescence was confirmed with electron microscopy.Microtubules are not evident in Sertoli cell regions surrounding early spermatogenic cells, but are abundant in cytoplasm adjacent to apical crypts containing elongate spermatids. In regions surrounding crypts, microtubules are uniformly aligned parallel to the long axis of Sertoli cells. Microtubules in these more central, or columnar, regions of the cells extend from supranuclear levels to the apex of the epithelium. In apical processes surrounding late spermatids, microtubules conform to the contours of the hook‐shaped spermatid heads. These microtubules appear continuous with those in the columnar regions of the Sertoli cells.Changes in microtubule distribution observed in the rat are generally similar to, but less elaborate than, those reported previously in the squirrel. These changes may be characteristic of mammalian spermatogenesis in general.
Effects of starvation, feeding, and time of day on the activity of proton transport adenosine triphosphatase in the parietal cells of the mouse gastric glands
Authors: Coulton Gary R. , Firth J. Anthony 
Published: February 2005

AbstractThe effects of starvation, feeding, and time of day on mouse gastric glands were studied by means of an enzyme histochemical method for K+ ‐dependent p‐nitrophenyl phosphatase (K+ ‐NPPase), a partial reaction of the proton pump AT‐ Pase which drives gastric acid secretion. The stomachs of mice starced for 24 h showed very low levels of parietal cell K+ ‐NPPase histochemical reaction. However, a brief meal following such a period of starvation produced an abrupt increase in K+ ‐NPPase reaction within most of the parietal cell‐containing glands though not all parietal cells were equally susceptible to stimulation. The number of glands containing K+ ‐NPPase‐reactive cells fell slowly in the hours following a feeding stimulus. These changes were shown to be causeds by feeding rather than by general arousal and to follow the feeding cycle in and libitum fed animals. The reasons that parietal cells in the basal parts of mouse gastric glands cannot be induced to show K+ ‐NPPase reactivity by a feeding stimulus are not understood.
Specific configurations of fibronectin‐containing particles correlate with pathways taken by neural crest cells at two axial levels
Authors: Brauer Philip R. , Markwald Roger R. 
Published: February 2005

AbstractAlthough neural crest (NC) cells can potentially enter a number of intertissue spaces, they select a particular pathway that varies depending on the axial level. In the cranial region, NC cells enter the dorsal‐lateral pathway (i.e., immediately subjacent to the ectoderm) and avoid the ventral pathway (i.e., pathway between the mesoderm and neural tube and within the mesodermal cell population), whereas in the trunk region, the majority of the NC cells enter the ventral pathway (i.e., between the somite and neural tube) and not the dorsal‐lateral pathway. Our working hypothesis is that one determining factor in directing NC cell migration is the composition and/or intermolecular associations of the extracellular matrix (ECM) in these pathways. Histochemical staining, immunostaining, and lectin‐binding studies on cryofixed and conventionally fixed tissue were conducted to initially characterize the ECM found in potential NC cell pathways prior to and during initial NC cell migration at two different axial levels. We found that, regardless of the axial level, the pathways into which NC cells eventually enter possessed a characteristic ECM arrangement. This arrangement included: (1) the presence of multicomponent, glycoprotein‐containing spherical particles (0.1–0.5 μm in diameter); and (2) a low‐sulfated ECM content. Although all particles contained fibronectin, only those in specific regions were able to bind to a monoclonal antibody directed to the cell‐binding domain of fibronectin, suggesting that the conformation of fibronectin may be important in the expression of any in situ function of the molecule.
Lumbrical muscle function as revealed by a new and physiological approach
Authors: Ranney Donald , Wells Richard 
Published: February 2005

AbstractThe lumbrical muscle is clearly one of several possible extensors of the interphalangeal joints. With an origin on the flexor digitorum profundus tendon it is credited with unloading the elastic tension across the interphalangeal joints and thereby facilitating their extension. Its role at the metacarpophalangeal joint is not a matter of universal aggreement. Attempts to simulate its action with weights over pulleys have not clarified this role, since true simulation would require the development of a means of applying force along the course of the lumbrical without pre‐determining which end would move. Such a system is herein described; it uses a Bowden cable, which is commonly used to activate the brakes of a bicycle. After constructing length‐tension curves of the profundus muscle in four fresh cadavers prior to the onset of rigor mortis, the interaction of realistic lumbrical loads with profundus elastic tension was studied. By contraction a lumbrical muscle adds a small but significant flexor force at the metacarpophalangeal joint, and thereby it is also capable of contributing to radial deviation and possibly rotation. As it runs from a flexor tendon to an extensor tendon and is endowed with a great many muscle spindles the lumbrical could play a part in the control of finger movement by monitoring the rate of hand closing during grasp.
Light and scanning electron microscopic observations of the canalicular system in human cellular cementum
Authors: Ismail Osama S. , Weber Dennis F. 
Published: February 2005

AbstractA scanning electron microscopic cast technique was used to determine the nature of the canalicular system in human cellular cementum. Prior light microscopic observations suggested the presence of two distinct types of lacunae: bonelike and a large irregular type generally confined to the interradicular region. Only the bone‐like lacunae were visualized in the SEM cast preparations. The canalicular system associated with the bone‐like lacunae was usually continuous from the surface of the dentin to the surface of the cementum in newly‐erupted teeth. Casts having a sponge‐like configuration were observed near the cementodentinal junction in some of the specimens from the interradicular region. The presence of these casts could not be predicted from prior light microscopic observations and it was concluded that they may represent infiltration of hypomineralized matrix rather than lacunae.
Distribution of the mineralized tissues in the nasal ventral conchae (Os conchae nasalis ventralis) of pigiets after birth: Relationship with atrophic rhinitis
Authors: Trépanier Hélène , Martineau Guy‐Pierre , Martineau‐Dlzé Béatrice 
Published: February 2005

AbstractSerial undecalcified cross sections were examined in order to establish the distribution of calcified cartilage, woven and lamellar bones in the nasal ventral conchase of piglets aged between birth and six weeks. The distribution of the mineralized tissues varied according to the age of the piglets and to the level of cross sections. The nasal ventral conchae were found to arise from an ossification center located at the level of the second premolar tooth. A correlation between the distribution of the different mineralized tissues of the nasal ventral conchae and the distribution of the lesions of atrophic rhinitis in the nasal ventral conchae as well as the receptivity period of piglets to the disease as observed in the literature have been discussed.
Changes in the pattern of intercellular transfer of Lucifer yellow between villus epithelial cells during postnatal development
Authors: Cheng Hazel , Bjerknes Matthew 
Published: February 2005

AbstractWe demonstrate the pattern of intercelluar transfer of Lucifer yellow between villus epithelial cells during postnatal development. Epithelial cells in all villi from newborn mice demonstrate high dye transfer efficiency. The efficiency of dye transfer decrease with the age of the mouse and with villus size, until in adult mice, dye transfer is observed only in what are presumably newly forming villi. We suggest that the development of an osmolality gradient in taller villi, a result of sodium pumps and a countercurrent multiplier, may be responsible for the changes in the pattern of dye transfer observed.
Clinical prosection for dental gross anatomy: A medial approach to the pterygomandibular space
Authors: Shaw Marjorie D. , Fierst Patricia 
Published: February 2005

AbstractThis paper describes a prosection of the pterygomandibular space from a medial perspective, as the dentist would encounter it. The prosection is performed on a bisected head, with vertebrae removed. The preparation can be used to demonstrate to the student the exact course of a needle during an inferior alveolar nerve block. The anatomical structures involved in performing the conventional, Gow‐Gates, or Akinosi injection techniques are directly compared. The impingement of a misplaced needle on neighboring structures can be demonstrated.