bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ultrastructure of the human anogenital “sweat” gland
Authors: van der Putte S. C. J. 
Published: February 2005

AbstractA newly described type of cutaneous gland occurring in the human anogenital region was investigated in specimens from the vulva by electron microscopy. This gland, which is characterized by a long excretory duct opening at the skin surface, by a wide coiled secretory part with multiple lateral extensions in the form of diverticula and branches lined by a two‐layered pseudostratified of myoepithelium, and by a luminal layer of tall columnar cells with conspicuous “snouts”, could not be categorized as an eccrine, apocrine, or mammary gland. Electron microscopy confirmed its separate position by showing that the luminal layer of secretory cells with prominent cytoplasmic caps had elaborately folded lateral membranes, occasional canaliculi, and a large number of uniform electron‐lucent to moderately electron‐dense secretory granules as part of a probable merocrine secretion. The excetory duct showed a poorly developed cuticular border. This combination of ultra‐structural features is alien to the other tubular cutaneous glands. The function of this anogenital “sweat” gland remains obscure, but the presence of these granules suggests a secretion product that is different from that of other cutaneous glands. © 1993 Wiley‐Liss, Inc.
Isolation of chick primordial germ cells from stages 4–8 embryos
Authors: Matsumura George , England Marjorie A. 
Published: February 2005

AbstractChick embryo primordial germ cells (PGCs) stages 4–8 were manually isolated for the first time from the late hypoblast layer. They were confirmed to be PGCs by periodic acid‐Schiff (PAS) staining and examination by scanning electron microscopy (SEM). They were subsequently introduced onto a variety of artificial substrata. On two dimensional substrata, the cells change from a spherical shape covered with numerous microvilli to a rounded cell with a “skirt” of cytoplasm. Eventually a process projects from one side of the smooth cell.On a three dimensional substrate the PGCs change from a spherical shape covered with numerous microvilli to a smooth surfaced cell with a long single process.It is concluded that the PGCs which are originally spherical in situ in stage 4 alter their morphology both in vivo during their migration and in vitro studies. © 1993 Wiley‐Liss, Inc.
Long‐term selective culture of hamster pulmonary endocrine cells
Authors: Linnoila R. Ilona , Gazdar Adi F. , Funa Keiko , Becker Kenneth L. 
Published: February 2005

AbstractWe describe, for the first time, the development of a technique for a long‐term selective culture of endocrine (PE) cells from the lungs of normal animals. Epithelial cells were isolated from 1‐day‐old hamster lungs through mechanical and enzymatic dissociation with collagenase type II. Cells were then cultured in HITES medium which contained RPMI 1640, hydrocortisone, insulin, transferrin, estradiol, sodium selenite, and supplemented with 5% fetal bovine serum (FBS), or medium which contained HITES medium supplemented with bovine serum albumin, phosphoethanolamine, arginine vasopressin, bombesin, and 2% FBS (9N). HITES medium, originally developed for establishment and long‐term culture of human small cell lung cancer (SCLC) cell lines, allowed propagation of normal hamster PE cells up to 12 months as a mixed floating‐attached cell culture. No difference was noted in the results using HITES or 9N. By 3 months, 80% of the cultured cells contained characteristic dense‐core (endocrine type) granules. The cultured PE cells also expressed creatine kinase brain isoenzyme, and general NE markers including neuron specific enolase, and amine handling enzyme activity within the range of SCLC cell lines. Moreover, cultured PE cells contained and secreted immunoreactive calcitonin (iCT) which had a molecular profile similar to that of intact hamster lung. This long‐term culture technique should markedly assist in elucidating the role of PE cells in health and disease. © 1993 Wiley‐Liss, Inc.
Dynamics of epithelial cells in the corpus of the mouse stomach. IV. Bidirectional migration of parietal cells ending in their gradual degeneration and loss
Authors: Karam Sherif M. 
Published: February 2005

AbstractThe life story of parietal cells has been investigated in the corpus of the mouse stomach using electron microscopy and 3H‐thymidine radioautography. Parietal cells are scattered in the four regions of the unit. On the average 3.6 cells are in the pit, 6.2 in the isthmus, 5.6 in the neck, and 10.6 in the base. Parietal cells do not divide. They arise from partially differentiated pre‐parietal cells, which are believed to be derived in the isthmus from the three subtypes of granule‐free cells: undifferentiated cells, pre‐pit cell precursors, and pre‐neck cell precursors. Radioautography indicates that the transformation of granule‐free cells into pre‐parietal cells takes at least one day. The pre‐parietal cells, of which there are 0.6 per unit on the average, develop into parietal cells through three successive stages. Stage 1 is characterized by small immature cells that are identified by long apical microvilli. Stage 2 is characterized by larger cells, about one‐third the size of parietal cells, and by an incipient canaliculus and a few apical tubulovesicles. Stage 3 is characterized by the expansion of the canalicular and tubulovesicular systems as well as mitochondrial enlargement, which cause the pre‐parietal cell to gradually approach the size of, and eventually become, a parietal cell. This cell sequence mainly takes place in the isthmus, but may extend to the neck region.Continuous infusion of 3H‐thymidine confirms that parietal cells originate in the isthmus and that they migrate in two directions: some go outward to the pit and the others migrate inward to the neck and eventually to the base. It has been estimated that for every six parietal cells produced per month in the isthmus, three migrate to the pit and three migrate to the neck to eventually reach the base.While almost all parietal cells in the isthmus and neck appear normal, a large proportion of those reaching the pit (21%) and base (23%) undergo gradual alteration and degeneration. After the ensuing death, parietal cells are eliminated in one of two major ways: (1) extrusion into the gastric lumen, if they appear necrotic, or (2) phagocytosis by a neighboring cell or even by an invading connective tissue macrophage, if they are apoptotic. The overall turnover time of parietal cells averages 54 days.Briefly, a sequence of cells—the parietal cell lineage—is initiated in the isthmus, where the three subtypes of granule‐free cells are presumed to give rise to pre‐parietal cells, which then differentiate into parietal cells. Half of the parietal cells migrate away in the direction of the gastric lumen and gradually degenerate as they approach the free surface, while the other half migrate in the other direction toward the unit's blind end, where they degenerate and are eliminated. © 1993 Wiley‐Liss, Inc.
Tapering of the intrafascicular endings of muscle fibers and its implications to relay of force
Authors: Eldred E. , Ounjian M. , Roy R. R. , Edgerton V. R. 
Published: February 2005

AbstractThe geometric shape of the filamentous, intrafascicular type of muscle fiber ending was reconstructed as a basis for understanding the pattern in relay of the fiber's force to the muscle tendon. Single motor units (MUs) identified physiologically as being fast and slow, respectively, were isolated in cat tibialis muscles and glycogen‐depleted for recognition in cross sections of the muscle frozen at its Lo. Serial measurements of cross‐sectional area (CSA) using an image processing system were made along 14 intrafascicular endings of MU fibers and an additional seve, nondepleted fibers identified histochemically as slow. Comparison of coefficients of variation for the linear relation of the CSAs and of the equivalent diameters with length along the taper indicated that in both fast and slow fibers the areas bore a closer relationship, that is, the taper had the equivalent of a parabolic, rather than a conical outline. The implications of these two conformations to relay of the fiber's contractile force to surrounding structures are displayed graphically. © 1993 Wiley‐Liss, Inc.
Long‐term osteopenic changes in cancellous bone structure in ovariectomized rats
Authors: Miller S. C. , Wronski T. J. 
Published: February 2005

AbstractCancellous bone mass decreases following ovariectomy in rodents, providing a useful model for post‐menopausal bone loss in humans. This study describes and quantifies the longer‐term changes in cancellous bone structure in the ovariectomized (OVX) rat. Rats were OVX or sham‐OVX at 100 days of age and bones were collected 540 days later. Lumbar vertebral bodies were prepared for microradiography and structural analyses (nodal analyses and star volume analyses) of cancellous bone. Proximal humerii were prepared for scanning electron microscopy (SEM). Microradiography confirmed the loss of cancellous bone from the central spongiosa regions of the vertebral bodies and the humerii in the OVX rats. Changes in trabecular structural elements included relative increases in the number of free to free, cortical to free, cortical to node struts and decreases in the node to node struts in the OVX animals compared with controls. There were increases in average lengths of the node to free, node to node, and free to free trabecular struts in the OVX animals. The marrow star volume was increased in the OVX animals indicating a greater trabecular separation in these animals compared with controls. Viewed by SEM, metaphyseal trabeculae in the controls consisted of rods and plates but in the OVX animals the remaining trabeculae were mostly longitudinal rods with smaller transverse connecting rods. The remaining bone in the OVX animals was found in the lateral metaphyseal areas and is consistent with maintenance of the structural capacity of the bone. These long‐term changes in cancellous bone structure are likely due to the continuation of functional skeletal loading but a decrease in gonadal hormones resulting in a decreased necessity to maintain a skeletal mineral store for reproduction (e.g., pregnancy and lactation). © 1993 Wiley‐Liss, Inc.
Cardiac conduction system in the chicken: Gross anatomy plus light and electron microscopy
Authors: Lu Ying , James Thomas N. , Yamamoto Shoji , Terasaki Fumio 
Published: February 2005

AbstractTwenty‐three chicken hearts were used to study the cardiac conduction system by light and electron microscopy. In addition to a sinus node, atrioventricular node (AVN), His bundle, left and right bundle branches (LBB, RBB), the chicken also has an AV Purkinje ring and a special middle bundle branch (MBB). The sinus node lies near the base of the lower portion of the right sinoatrial valve. The AV node is just above the tricuspid valve and anterior to the coronary sinus. The His bundle descends from the anterior and inferior margin of the AV node into the interventricular septum, then dividing into right, left and middle branches some distance below the septal crest. The middle bundle branch turns posteriorly toward the root of the aorta. The AV Purkinje ring originates from the proximal AV node and then encircles the right AV orifice, joining the MBB to form a figure‐of‐eight loop. The chicken conduction system contains four types of myocytes: (1) The P cell is small and rounded, with a relatively large nucleus and sparse myofibrils. (2) The transitional cell is slender and full of myofibrils. (3) The Purkinje‐like cell resembles the typical Purkinje cell, but is smaller and darker. (4) The Purkinje cell is found in the His bundle, its branches, and the periarterial and subendocardial Purkinje network. © 1993 Wiley‐Liss, Inc.
Vascularization of the pineal complex in the lizard Tiliqua rugosa
Authors: Teo E. H. , Carati C. , Firth B. T. , Barbour R. A. , Gannon B. 
Published: February 2005

AbstractThe vascularization of the pineal complex in the lizard Tiliqua rugosa was investigated by vascular corrosion and latex casting techniques. The fine structure of the pineal capillaries was also studied by transmission electron microscopy. The pineal complex in T. rugosa consists of an elongated pineal gland proper and a separate, distinct parietal eye. The pineal complex derives an abundant blood supply from branches of the middle and posterior cerebral arteries. Scanning electron microscopy of vascular corrosion casts revealed a dense and extensive pineal capillary bed which drains ultimately into a wide longitudinal sinus suggesting an efficient pathway for the rapid removal of substances secreted by the gland. The parietal eye, which receives a unilateral left‐sided blood supply from the unpaired anterior pineal artery, is shown to be a highly vascularized structure. The close morphological relationship between the pineal gland and dorsal sac, where the two structures apparently share the same blood vessels, suggests a functional relationship between them. The pineal capillaries are fenestrated with tight junctions between adjoining endothelial cells. Podia‐like abluminal extensions of the endothelial cells were observed in close relation to unmyelinated nerve bundles. The basal margin of the pineal parenchyma is highly invaginated with thin finger‐like cytoplasmic protrusions into the pericapillary space. Distinct bands of microfibrils form “struts” anchoring the pineal parenchyma to the endothelial wall. These features may have a role in the transfer of materials between the pineal gland and the blood stream. © 1993 Wiley‐Liss, Inc.
Effects of pretreatment with androgen or thyrold hormone on androgen‐induced proliferation of granular convoluted tubular cells in mouse submandibular glands
Authors: Fang Jun , Yamamoto Reiko , Takatsuka Daishiro , Tsuji Motomu , Terada Nobuyuki 
Published: February 2005

AbstractThe effects of pretreatment with androgen or thyroid hormone on androgen‐induced proliferation of granular convoluted tubular cells (GCT cells) in the submandibular glands of ovariectomized female BALB/c or C57BL/6 mice were investigated. The proliferation of GCT cells was estimated by their labeling index. Daily injections of 5α‐dihydrotestosterone (DHT) (100 μg/mouse/day) caused a transient increase in the labeling index of GCT cells of ovariectomized 60‐day‐old BALB/c mice during the first four injections, but injections of thyroxine (T4) (15 μg/mouse/day) did not. On the other hand, both DHT and T4 increased the esteroprotease activity, a marker of the differentiation of GCT cells, time dependently. Injections of DHT into ovariectomized 102‐day‐old BALB/c mice also caused a transient increase in the labeling index of GCT cells. However, pretreatment of ovariectomized 60‐day‐old BALB/c mice with DHT for 4 or 14 days completely abolished the DHT‐induced increase in the labeling index of 102‐day‐old mice, and pretreatment with T4 for 14 days reduced this increase. Pretreatment with DHT or T4 for 14 days did not affect the DHT‐induced increase in esteroprotease activity. Pretreatment of ovariectomized 60‐day‐old C57BL/6 mice with DHT for 14 days also completely abolished the DHT‐induced increase in the labeling index of GCT cells at the age of 102 days, but pretreatment with T4 for 14 days did not affect the increase. These results suggest that the proliferation of mouse GCT cells induced by androgen results in a complete abolition of their proliferative response to androgen, and that the effect of thyroid hormone on the proliferative response of GCT cells to androgen may differ in different strains of mice. © 1993 Wiley‐Liss, Inc.
Innervation distribution pattern, nerve ending structure, and fiber types in pigeon skeletal muscle
Authors: Torrella J. R. , Fouces V. , Palomeque J. , Viscor G. 
Published: February 2005

AbstractFour fiber types have been characterized in different pigeon skeletal muscles according to their innervation pattern (nerve ending structure and innervation distribution) and histochemical properties (SDH and m‐ATPase activities). All fast fibers, types IIA and IIB, present aggregated distribution of their nerve endings with “en plaque” structures and very low innervation frequencies. The two kinds of slow fibers recognized are multiple innervated and present higher innervation frequencies. However, type I fibers have nerve terminals in small knobs with uniform localization, whereas type III fibers present “en grappe” nerve endings, which tend to be randomly distributed. Fiber type composition of skeletal muscles has been found closely related to their biomechanical function. Fast fibers are predominant in muscles with an active role in locomotive movements, whereas slow fibers are mainly or exclusively located in postural muscles. © 1993 Wiley‐Liss Inc.
Effects of chronic fluoride exposure on morphometric parameters defining the stages of amelogenesis and ameloblast modulation in rat incisors
Authors: Smith Charles E. , Nanci Antonio , Denbesten Pamela K. 
Published: February 2005

AbstractThe response of ameloblasts to long‐term (6 weeks) exposure to 100 ppm fluoride was examined in continuously erupting mandibular incisors of female Sprague‐Dawley rats as compared to control rats receiving a similar diet (Teklad L‐356) but no sodium fluoride in their drinking water. After treatment, animals from both groups were perfused intravascularly with glutaraldehyde, and the incisors were removed and processed for light microscope morphometric analyses directly from 1 μm thick Epon sections. Other animals were injected intravenously with calcein (green fluorescence) followed 4 hours later by xylenol orange (red fluorescence) in order to reveal smooth‐ended ameloblast modulation bands and thereby allow quantification of parameters related to the creation and movement of modulation waves within the maturation zone of these teeth. The results indicated that rat incisors expressed four major changes in normal amelogenesis which could be attributed to the chronic fluoride treatment. First, ameloblasts produced a thinner than normal enamel layer by the time they completed the secretory stage and entered the maturation stage of amelogenesis. Second, enamel organ cells within the maturation zone, especially those from the papillary layer, were shorter in height than normal. Third, ameloblasts related to maturing enamel in areas where it was partially soluble and/or fully soluble in EDTA modulated at a rate that was much slower than normal. In some locations ameloblasts remained ruffle‐ended for as much as 30% longer than normal per cycle. This upset the usual pattern such that fewer total modulation cycles were completed per unit time by these ameloblasts. Fourth, enamel proteins were lost from the maturing enamel layer at a rate that was about 40% slower than normal. The data suggested that ameloblasts detected the delay in the extracellular breakdown and/or loss of enamel proteins and they responded by remaining ruffle‐ended for longer intervals than usual (positive feedback). © 1993 Wiley‐Liss Inc.
Presence and foveal enrichment of rod opsin in the “all cone” retina of the American chameleon
Authors: McDevitt David S. , Brahma Samir K. , Jeanny Jean‐Claude , Hicks David 
Published: February 2005

AbstractThe retinal photoreceptors of the eye of the American chameleon, Anolis carolinensis, have been considered to be exclusively cones. Its retina is unusual for possessing two foveas (areas associated with heightened visual acuity), with the major, central fovea deeply incised and very densely packed with photoreceptors. Immunoblotting and light‐ and electron microscopic‐immunocytochemistry, using several opsin monoclonal antibodies previously found specific for rods, demonstrated the presence and localization of this protein in the Anolis retina. This visual pigment appears sparsely in a subpopulation of photoreceptors in the periphery but overwhelmingly in the central fovea. Complementary results with cone‐specific antibody and lectin binding corroborated this spatial organization. These results, as well as those with geckos, suggest that photoreceptor morphology is not an accurate guide among the lacertilians to visual pigment content, and that this phylogenetic grouping may constitute a crossoads in vertebrate photoreceptor evolution. © 1993 Wiley‐Liss, Inc.
Immunohistochemical localisation of the 25 kDa heat shock protein in unstressed rats: Possible functional implications
Authors: Wilkinson Jenny M. , Pollard Irina 
Published: February 2005

AbstractThe distribution of the 25 kDa heat shock protein (hsp 25) in a number of tissue types from unstressed rats was investigated. Immunohistochemical analysis showed that hsp 25 was not found in the thymus, brain (cerebral cortex and cerebellum), testis, adrenal, liver, spleen, or kidney. A number of cells in the anterior pituitary showed strong staining. These cells were tentatively identified as being either gonadotropes or thyrotropes. Strong staining was also observed in the blood vessels within these tissues. Hsp 25 was found to be localised predominantly to intestinal smooth muscle of the duodenum and colon and to vascular smooth muscle. Smooth muscle from other sites, such as the trachea, was also intensely stained. Lower and more variable amounts of staining were observed in cardiac and skeletal muscle. These observations suggest that hsp 25 is associated with cytoskeletal elements in muscle, and that the high staining intensity in smooth muscle might be due to the lack of internal architecture present in this muscle type. © 1993 Wiley‐Liss, Inc.
Characterization of distal lymphoid nodules in the chicken caecum
Authors: del Cacho Emilio , Gallego Margarita , Sanz Albina , Zapata Agustin 
Published: February 2005

AbstractIn this report, we describe lymphoid nodules consistently found in the distal region of each chicken caecum at approximately 3 cm from the ileo‐cecal junction. These structures were studied by light microscopy both in normal and Eimeria tenella‐infected chickens. They were observed with the naked eye in infected birds but not in normal chickens. In these latter the region of the caecal lamina propria corresponding to that in which the lymphoid aggregates were visible revealed a light infiltration by diffuse lymphoid tissue as well as a few germinal centers. The distal lymphoid nodules were studied using a panel of monoclonal antibodies which are specific for chicken Ig‐containing cells, macophages, Ia‐like positive cells, and interdigitating cells, as well as a policlonal antiserum reactive with S‐100 protein to stain both interdigitating cells and follicular dendritic cells. The immunohistochemical study demonstrated the resemblance of these aggregates to the caecal tonsils, suggesting that they represent specialized mucosa‐associated lymphoid tissue that respond to antigens in the caecal lumen, their function being to enhance the mucosal defense provided by the caecal tonsils against antigens in the lumen of the caeca. © 1993 Wiley‐Liss, Inc.