bluuebunny/crossref_metadata_2025_split huggingface dataset:
Liver of juvenile atlantic salmon, Salmo salar L.: A light, transmission, and scanning electron microscopic study, with special reference to the sinusoid
Authors: Speilberg Lars , Evensen Øystein , Nafstad Per 
Published: February 2005

AbstractBackground: This report provides a detailed description of sinusoidal and perisinusoidal structures in the normal liver of the juvenile Atlantic salmon (Salmo salar L.), a teleost species.Methods: The liver was studied by light, transmission, and scanning electron microscopy, and organ specimens were sampled after retrograde, whole‐body perfusion through the dorsal aorta using 3% glutaraldehyde. Detailed characterization of perisinusoidal stellate cells also included immunohistochemical staining for desmin and evaluation of autofluorescence of the same cells upon excitation in ultraviolet (UV) light.Results: The sinusoid is lined by one cell type only: the endothelial cell. No intraluminal pit cells or Kupffer cells are present. The space of Disse contains reticulin fibres, visualized by Gomori's silver stain, and perisinusoidal stellate cells (PSC). PSC exhibited autofluorescence in UV light, indicating that these cells store vitamin A in cytoplasmic lipid droplets. Immunohistochemically, PSC were found negative for desmin. The space of Disse, extending deep down between adjacent hepatocytes, receives long, slender microvilli from parenchymal cells. In addition to scattered macrophages, interhepatocytic cells (IHC) are found perisinusoidally. Hepatocytes of Atlantic salmon form branching and anastomosing tubules.Conclusions: The sinusoids of Atlantic salmon liver are lined by a fenestrated endothelium, with PSC located in the space of Disse, with macrophages and IHC as inhabitants of the interhepatocytic space. IHC show ultrastructural similarities to mammalian pit cells and teleostean large granular lymphocytes, as well as to piscine monocytes. PSC might be storage cells for vitamin A in Atlantic salmon as shown by autofluorescence in these cells, while immunohistochemical studies indicate that desmin does not seem to be an adequate immunohistochemical marker for PSC in the juvenile Atlantic salmon. Methodologically, fixation for electron microscopy was performed by a new and convenient perfusion method: arterial retrograde whole body perfusion. Liver specimens intended for scanning electron microscopy were fractured at room temperature after prolonged osmium postfixation, leaving hepatocytes intact and producing images well suited to document the three‐dimensional structure of cells and tissue. © 1994 Wiley‐Liss, Inc.
Perspectives: A vital biomechanical model of the endochondral ossification mechanism
Authors: Frost Harold M. , Jee Webster S. S. 
Published: February 2005

AbstractBackground: Mechanical usage effects could explain many features of endochondral ossification and related processes. Mineralization of growth plate cartilage could reduce its mechanical strains enough to make its resorption begin and to guide it in space. By removing most of its mineralized vertical septae, resorption could overload the remainder enough to increase woven bone formation on them and construct the primary spongiosa. After it finishes mineralizing, the primary spongiosa could become stiff enough to begin partial disuse in strain terms, so BMU‐based remodeling would begin replacing it with lamellar bone. This would construct the secondary spongiosa. In transferring loads from the growth plate to the cortex, the central metaphyseal spongiosa becomes deloaded. This disuse would make remodeling remove it in the diaphyseal marrow space.Methods: The slow growth of epiphyses and apophyses gives their spongiosas more time to adapt to their loads than the metaphyseal spongiosa beneath faster growing growth plates. Compared to metaphyseal trabeculae, this leads to fewer and thicker epiphyseal trabeculae that turn over more slowly and should persist for life because they carry loads for life.Results: Rapid turnover of metaphyseal cortex in very young subjects could let it strain enough to form woven bone. Increased thickness and slower turnover of this cortex in older subjects could reduce its strains enough to make lamellar bone form there instead. This would compose this cortex mostly of woven bone in the very young and of lamellar bone in adults.Conclusions: This model assigns particular importance to the stiffness and strains of tissues (as distinguished from their strength and stresses), to the relative rates of some processes, and to responses of the skeleton's biologic mechanisms to a tissue's typical largest mechanical strains (as distinguished from their stresses). © 1994 Wiley‐Liss, Inc.
Perspectives: Applications of a biomechanical model of the endochondral ossification mechanism
Authors: Frost H. M. , Jee W. S. S. 
Published: February 2005

AbstractA biomechanical model of endochondral ossification (Frost and Jee, 1994. Anat. Rec., 240:435–446) can help to explain: (1) some differences in fracture patterns in children and adults, (2) increased fractures during the human adolescent growth spurt, (3) localization of stress fractures and pseudofractures to cortical instead of trabecular bone, (4) increased bone mass in adult‐acquired and childhood obesity, (5) subchondral bone densification and osteopenia in some arthroses, (6) why and where mammals lose spongiosa with aging, (7) why, as percents of the original bone stock, metaphyseal trabecular bone losses with aging usually exceed cortical bone losses, (8) why osteochondritis dissecans and aseptic necroses of bone localize in epiphyses instead of metaphyses, (9) some features of growth plate histology in rickets and the chondrodystrophies, (10) why spontaneous fractures in osteoporotic patients affect vertebral more than metaphyseal spongiosa, (11) why osteopenias develop in most chronic, debilitating diseases, and (12) why histomorphometric values can differ in iliac bone biopsies obtained by the “vertical” Jamshidi and “horizontal” Bordier‐Meunier techniques. © 1994 Wiley‐Liss, Inc.
Connections between the various elements of the Cis‐ and mid‐compartments of the Golgi apparatus of early rat spermatids
Authors: Clermont Y. , Rambourg A. , Hermo L. 
Published: February 2005

AbstractBackground: The exact structural relationships of the saccules, membranous tubules, and vesicles that compose the cis‐ and midcompartments of the Golgi cortex of rat spermatids was investigated to determine the relationship of these elements to each other.Methods: Tissues fixed with glutaraldehyde and buffered in sodium cacodylate were examined with the electron microscope. Electron micrographs, including stereopairs, were analyzed to determine the three‐dimensional organization of the Golgi elements.Results: The deeper layer of the Golgi cortex was composed of stacks of saccules connected to each other either by saccules or membranous tubules. The peripheral region of the Golgi cortex, located between the cisside of the stacks and a network of overlying ER cisternae contained numerous membranous tubules and vesicles of two class sizes: 50–100 nm vesicles and microvesicles 5–10 nm in diameter. The tubules formed tight networks, known as cis‐elements or cis‐Golgi networks (CGN), which were strictly parallel and next to the first or cis‐saccule of the stack. The cis‐elements were continuous with more loosely arranged peripheral tubules which formed elaborate, intertwined and interconnected networks. These peripheral tubules closely approximated the overlying ER cisternae in areas often showing fuzz‐coated finger‐like projections. Occasionally such peripheral tubules were continuous with ER cisternae. The saccules forming the stacks were continuous with membranous tubules which not only connected saccules of adjacent stacks, but also saccules of the same stack. These tubules were also connected with the tight tubular networks forming the cis‐elements and the broad networks formed by the peripheral membranous tubules. Vesicles (50–100 nm) and microvesicles (5–10 nm) frequently formed aggregates in the peripheral Golgi region next to areas of ER membrane free of fuzz‐coated projections. The microvesicles, embedded in a denser cytoplasmic matrix, had a more or less distinct delimiting membrane suggestive of their disintegration in this juxta‐ER location. The 50–100 nm vesicles that were seen at the periphery of the vesicular aggregates appeared to form mainly from the membranous tubules of the Golgi cortex.Conclusions: Thus the saccules and membranous tubules of the spermatid's Golgi cortex formed a single continuous membranous system connected to ER cisternae. The vesicles, seemingly arising from the membranous tubules, appear to follow a retrograde pathway and undergo dissolution next to ER cisternae. © 1994 Wiley‐Liss, Inc.
Type and regional diversity in the distribution of myosin heavy chains in chicken intrafusal muscle fibers
Authors: Maier Alfred 
Published: February 2005

AbstractBackground: Chicken intrafusal fibers were classifed on the basis of their myosin heavy chain (MHC) composition, which was compared to that of mammalian nuclear bag and nuclear chain types.Methods: Immunoreactivities of intrafusal fibers from leg muscles of 8‐week‐old chickens were evaluated in serial cross‐sections after incubation with monoclonal antibodies against slow‐twitch, slow‐tonic, or fast‐twitch MHC and fast muscle C‐protein.Results: Four categories of slow intrafusal fiber could be distinguished on the basis of differential expression of slow‐twitch and slow‐tonic MHC. Segregation into types was most evident at the motor axon supplied pole, followed by the sensory region of the equator. Fiber types were least distinct at the juxtaequator where sensory and motor axons meet. Intrafusal fibers negative for slow myosins reacted with anti‐fast myosins. Fast fibers were best viewed as a single group without subdivisions. Immunostaining for fast muscle C‐protein paralleled in large part reactivities for neonatal/fast MHC, indicating that proteins other than MHC are useful fiber type markers.Conclusions: Despite regional changes along the length of intrafusal fibers and some variation within fiber types, the concept of separate MHC‐based fiber types was valid as long as typing of fibers was restricted to the proximal polar region. Comparisons of MHC profiles revealed similarities between chicken fast intrafusal fibers and mammalian nuclear chain fibers and between some chicken slow intrafusal fibers and mammalian nuclear bag fibers. © 1994 Wiley‐Liss, Inc.
Immunocytochemical detection of actin and 53 kDa polypeptide in the epididymal spermatozoa of rat and mouse
Authors: Paranko Jorma , Yagi Ahmed , Kuusisto Mari 
Published: February 2005

AbstractBackground: Presence of immunocytochemically detectable actin in the rat and mouse sperm head has been enigmatic for years. In this study, we demonstrate actin in the perinuclear theca and show that the detection of actin epitopes in the rat and mouse epididymal spermatozoa can effectively be enhanced by pre‐extraction of sperm cells with SDS.Methods: The study with one monoclonal and one polyclonal anti‐actin antibody was carried out at conventional and confocal fluorescence and electron microscope level, and by immunoblotting of proteins isolated from the head and tail fractions.Results: In the head of the control methanol‐acetone fixed rat spermatozoa, the polyclonal antibody gave a stronger immunostaining in the postacrosomal area and in the perforatorium than the monoclonal antibody. In the mouse sperm head, the monoclonal antibody labeled the ventral edge of the postacrosomal area and slightly the perforatorium, whereas the polyclonal antibody stained the entire perinuclear space. In the SDS‐extracted spermatozoa, an intense postacrosomal and perforatorial labeling was obtained with both antibodies but, in particular in the rat spermatozoa, the middle lateral portion of the postacrosomal segment remained unlabeled. Sonication seemed to cause structural modifications which specifically impeded staining with the monoclonal antibody. Both antibodies detected actin in the basal plate and the monoclonal antibody in the neck. Amorphous matrix of the connecting piece showed immunogold labeling. In the tail, the monoclonal antibody recognized actin and a relatively basic 53 kDa polypeptide, whereas the polyclonal antibody reacted with several protein bands. SDS‐soluble actin of the tail was addressed to the midpiece and the SDS‐insoluble 53 kDa protein profoundly to the outer dense fibers of the principal piece.Conclusions: Intense labeling of actin in the SDS‐extracted rat and mouse spermatozoa was presumably due to the generated demasking of actin epitopes embedded in the perinuclear cytoplasm. The results are important in confirming that actin in the rat and mouse sperm head is not lost during spermiogenesis but apparently contributes to the three‐dimensional packing of the mature perinuclear cytoplasm. This study further demonstrates the importance of the methods used in sample preparation and advantages of conofocal microscopy when attempting to detect cytoskeletal proteins which, as in spermatozoa, may occur in small quantities. © 1994 Wiley‐Liss, Inc.
Maturation of undifferentiated lung epithelial cells into type II cells in vitro: A temporal process that parallels cell differentiation in vivo
Authors: Chinoy Mala R. , Antonio‐Santiago Maria T. , Scarpelli Emile M. 
Published: February 2005

AbstractBackground: Formation of alveolar‐like structures (ALS) by mature fetal rabbit type II pneumocytes (day 29 gestation) and long‐term differentiation on Engelbreth‐Holms‐Swarm mouse tumor extract or EHS gel (Matrigel) were reported by our group (Blau et al., 1988. J. Cell Physiol., 136:203–214). We now describe structural organization and differentiation of immature lung epithelial cells, isolated at day 22 gestation, into mature type II cells in vitro.Methods: Peripheral pulmonary tissue was pooled and undifferentiated epithelial cells isolated for primary culture on Matrigel. Cells were examined 12–16 h after plating and on days 1,3,5, and 7 of culture and assessed by phase contrast and by transmission electron microscopy after fixation in situ.Results: Cells formed ALS 12–16 h after plating. Spherule diameter increased about four to eight times from day 1–7 in culture. There was rapid transformation of tall columnar cells to cuboidal, normal polarization of cells with respect to cell‐free lumen of ALS, progressive reduction of glycogen zones, apparent gradual increase of cell organelles such as Golgi apparatus, rough endoplasmic reticulum and mitochondria, and apparent extrusion of lipidic figures into the lumen. These morphologic transformations in vitro temporally paralleled cell differentiation in vivo. The relative increase of 14C‐acetate precursor into phosphatidylcholine in contrast to cardiolipin was consistent with these transformations.Conclusions: Under the conditions of our culture system, maturation of undifferentiated pulmonary epithelial cells is reproduced in vitro along the same time course and according to the same developmental sequence of fetal lungs in vivo. © 1994 Wiley‐Liss, Inc.
Formation of alternating tiers in the optic chiasm of the chick embryo
Authors: Drenhaus Ulrich , Rager Günter 
Published: February 2005

AbstractBackground: When the fibers of the two optic nerves of the chick cross to the contralateral side at the prospective chiasmatic region, they segregate into clearly defined bundles. These bundles form horizontally oriented tiers which alternate between the right and the left optic nerve.Methods: We have analyzed the development of these tiers qualitatively and quantitatively using light and electron microscopy between embryonic days (E) 4 and E19.Results: The formation of the chiasm begins on E4. In the course of E4, tiers become visible for the first time. Their number increases rapidly until E7. Then the increase is slowed down and the final value (32 ± 1) is approximated by E18/19. Growing axons allow one to distinguish three different segments: the growth cone, the distal, and the proximal segment. The latter originates in the perikaryon. Growth cones and distal segments are found predominantly in the ventralmost tiers. Their frequency decreases from ventral to dorsal. Proximal segments which indicate the presence of older axons appear first in the dorsal tiers and later also in more ventrally located tiers.Conclusion: Based on these criteria it is concluded that newly formed axons contribute primarily but not exclusively to the ventral tiers. There is a gradient of maturity of axons from ventral to dorsal whose slope becomes steeper with age until the last growth cones have arrived by E18. Thus, the formation of the chiasm corresponds to the spatiotemporal pattern of ganglion cell formation in the retina. The process of cell death of retinal ganglion cells is also seen in the chiasm but probably does not lead to a transitory diminution in the number of tiers. © 1994 Wiley‐Liss, Inc.
Immunohistochemical localization of the high‐affinity NGF receptor (gp 140‐trkA) in the adult human dorsal root and sympathetic ganglia and in the nerves and sensory corpuscles supplying digital skin
Authors: Vega J. A. , Vazquez E. , Naves F. J. , Del Valle M. E. , Calzada B. , Represa J. J. 
Published: February 2005

AbstractBackground: Nerve growth factor (NGF) is produced in target issues of sympathetic and neural‐crest derived sensory neurons, including skin, to provide them trophic support. The biological effects of NGF on responsive cells are mediated by specific high‐affinity receptors. Recently, a protein tyrosine kinase of ≃ 140 kDa molecular weight, encoded by the proto‐oncogene trkA, has been identified as the high‐affinity NGF receptor (gp140‐trkA). The present work was undertaken to study the localization of gp140‐trkA‐like immunoreactivity (IR) in human peripheral ganglia (sympathetic and dorsal root ganglia), and in glabrous skin.Methods: Lumbar dorsal root ganglia, para‐ and prevertebral sympathetic ganglia, and digital glabrous skin were studied immunohistochemically using a rabbit anti‐gp140‐trkA polyclonal antibody. In order to accurately establish the localization of gp140‐trkA IR, the neurofilament proteins and S‐100 protein were studied in parallel in: (1) sensory and sympathetic ganglia, to label neuron cell bodies and satellite or supporting cells, respectively; (2) human skin, to label axons, Schwann and related cells within nerves and sensory corpuscles. Moreover, a quantitative study (neuron size, intensity of immunostaining) was carried out on sympathetic and dorsal root ganglia neuron cell bodies.Results: A specific gp140‐trkA‐like IR was found in: (1) a subpopulation (65%) of primary sensory neuron cell bodies, including most of the largesized ones but also small‐ and intermediate‐sized ones; (2) most of sympathetic neuron cell bodies (82%); (3) theineurial cell, Schwann cells, and large axons of the nerve trunks supplying digital skin; (4) the lamellar cells of Meissner corpuscles; (5) the central axon, inner‐core, outer‐core, and capsule of Pacinian corpuscles. In addition, the occurrence of gp140‐trkA‐like IR was observed in some non‐nervous tissues of the skin, including epidermis (mainly in the basal layer), sweat glands, and arterial blood vessels.Conclusions: Present results provide evidence for the localization of gp140‐trkA‐like IR in: (1) nerve cells which are known to be NGF‐responsive, and (2) non‐nervous cutaneous tissues which are innervated by NGF‐dependent peripheral neruons. These findings suggest that, in addition to the well‐established role of NGF on sensory and sympathetic neurons, this neurotrophin may be able to regulate some other functions on non‐nervous cell which are targets for NGF‐dependent peripheral neurons. © 1994 Wiley‐Liss, Inc.
Phagocytic defence mechanism in sea bass (Dicentrarchus labrax L.): An ultrastructural study
Authors: Angeles Esteban M. , Meseguer José 
Published: February 2005

AbstractBackground: The ultrastructure of the phagocytic process in fish has not been established in spite of the significant morphofunctional differences detected in the fish immune system with respect to the basic immunological pattern in vertebrates. We report the ultrastructure of the bacterial phagocytic defence mechanism in sea bass (Dicentrarchus labrax L.).Methods: Head‐kidney, blood, and peritoneal exudate leukocytes were challenged with Aeromonas salmonicida and Escherichia coli and processed for transmission electron microscopic study.Results: Macrophages challenged with bacteria showed changes in the cell outline, in the chromatin pattern, and in the ultrastructural features of the cytoplasm as a consequence of an activation process. The phagocytic process consists of the following: (1) Bacteria‐macrophage contact. One or more spot contacts between the bacterial wall and the phagocyte membrane are observed. (2) Bacteria engulfment. Slight depressions, membrane invaginations, or cytoplasmic processes are formed at the phagocyte surface. Macrophage processes occasionally surround the bacteria, overlaping and roaming parallel, or a single, long pseudopod encircles a bacterium several times. (3) Endocytic vesicle formation. Macrophages show one or more bacteria inside membrane‐bound cytoplasmic vesicles. (4) Phagolysosome formation. Some dense granules (lysosomes) fuse with the endocytic vesicle. (5) Intracelular killing/digestion. Bacteria inside the endocytic vesicles are observed both virtually intact or damaged at different digestion stages.Conclusions: Sea bass macrophages possess the mechanisms necessary to both engulf and kill bacteria. Cellular and subcellular events in the morphology of phagocytosis and lysosomal dissolution of bacteria fit the general pattern described for mammals. © 1994 Wiley‐Liss, Inc.
Anatomy of the hyoid apparatus in Odontoceti (toothed whales): Specializations of their skeleton and musculature compared with those of terrestrial mammals
Authors: Reidenberg Joy S. , Laitman Jeffrey T. 
Published: February 2005

AbstractBackground: The hyoid apparatus of odontocetes (toothed whales) serves as a major attachment point for many of the muscles and ligaments subserving breathing, swallowing, and sound production.Methods: This study examines the hyoid apparatus in 48 specimens of ten odontocete genera (Phocoena, Lagenorhynchus, Stenella, Delphinus, Tursiops, Grampus, Globicephala, Mesoplodon, Physeter, and Kogia) collected post mortem from beach strandings.Results: The odontocete hyoid apparatus, as that of their closest terrestrial relatives, the artiodactyls, is divisible into a basal portion (bashyal, paired thyrohyals) and a suspensory portion (paired ceratohyals, epihyals, stylohyals, and tympanohyals) connecting the basal portion to the skull base. Unlike other terrestrial mammals, the basal portion lies inferior to the laryngeal aditus, is flattened dorso‐ventrally, and is relatively large, thus providing a broad surface area for muscle attachments. The suspensory elements are not as flattened and are joined by synovial joints (except for epihyal‐stylohyal fusion). Muscular specializations include enlargement of those which retract the hyoid apparatus (e.g., sternohyoid) or control the tongue (e.g., styloglossus, hyoglossus). These muscles may be particularly important in a specialized prey capture behavior called suction feeding. In addition, the hyoid apparatus has a tilted placement, which allows asymmetrical enlargement of the piriform sinuses. Asymmetry is also seen in the muscular attachment between the larynx and the hyoid apparatus. The most pronounced differences from the basic pattern are observed in two families: Physeteridae and Ziphiidae.Conclusions: The derived position and shape of the odontocete hyoid apparatus may have evolved to subserve several specialized upper respiratory/digestive tract functions, such as simultaneous feeding (suction and swallowing) and sound production. © 1994 Wiley‐Liss, Inc.