bluuebunny/crossref_metadata_2025_split huggingface dataset:
Structure of the upper teeth of the filefish, Stephanolepis cirrhifer
Authors: Uehara Kiyoko , Miyoshi Sakuichiro 
Published: February 2005

AbstractThe teeth of the filefish were investigated with light and scanning electron microscopy. Anterior and posterior rows of pleurodont teeth are present in the maxilla. The teeth in the anterior row possess a large labial and small lingual surface and the teeth in the posterior row possess a small labial and large lingual surface. The enameloid consists of three layers–the outer, middle, and inner layer. The outer layer consists of fine, parallel crystallites oriented perpendicular to the surface. They are similar to the crystallites in enamel derived from ectoderm. In the middle layer the crystallites form parallel bundles that are oriented in the same direction as that of the crystallites in the outer layer. In the inner layer bundles of crystallites interlace with each other. The tubular structures and the terminal branches of the dentinal tubules are located among the crystallites in the inner layer. In the dentine numerous dentinal tubules radiate from the pulp cavity toward the periphery and are seen to curve slightly in an S‐shaped course. At the occlusal tip the alternating parabolic layers are seen and these are considered to be mineralized lines. The openings of the dentinal tubules are round or oval, surrounded by interlacing fibrils. The teeth are tightly fixed to the jawbone by bundles of fibrils. At the lower part of the lingual surface of the teeth in the anterior row and the labial surface of the teeth in the posterior row the bundles of fibrils start at the dentine and some fibrils run through connective tissue, while others terminate in projections of the jawbones. These structures are discussed in comparison with those of other species.
Development of specific antibody‐forming cells in various lymphoid organs of rabbit after intravenous antigen administration
Authors: van der Brugge‐Gamelkoorn Gerda J. , Kors Nel , van Rooijen Nico 
Published: February 2005

AbstractRabbits were intravenously primed and boosted with trinitrophenyl‐keyhole limpet hemocyanin (TNP‐KLH) and human serum albumin (HSA); both antigens were injected simultaneously. The localization of anti‐TNP‐antibodyforming cells (AFCs) and anti‐HSA‐AFCs was determined in various lymphoid organs of the rabbit.In all lymphoid organs of primed rabbits anti‐TNP‐AFCs outnumbered anti‐HSA‐AFCs, with the exception of the thymus, in which neither of them was encountered. In the spleen the antibody‐forming cells were mainly situated in the periphery of the periarteriolar lymphocyte sheaths (PALS) and in the coaxial sheaths of lymphoid tissue surrounding the terminal arterioles. In the lymphoepithelial organs AFCs were almost exclusively situated in the interfollicular areas, and in the lymph nodes largely in the medulla.An intravenous booster injection led to a secondary immune response (i.e., increase of AFCs) in the spleen. No visible change in the number of specific AFCs was observed in the lymphoepithelial organs. However, in the mesenteric and popliteal lymph node the number of anti‐TNP‐AFCs had increased tremendously.
The influence of vasovasostomy on testicular alterations after vasectomy in Lewis rats
Authors: Flickinger Charles J. , Herr John C. , Howards Stuart S. , Caloras Daniel , Yarbro E. Scott , Spell Donald R. , Gallien Thomas N. 
Published: February 2005

AbstractThe occurrence of alterations in testicular weight and morphology after vasectomy and vasectomy reversal by vasovasostomy was studied in Lewis rats. Animals were studied 3, 4, and 7 months after bilateral vasectomy or a vasectomy followed 3 months later by vasovasostomy. Other rats served as shamoperated controls. The weights of the testes in vasectomy and vasovasostomy animals fell into two groups—small testes weighing less than 0.88 g and normal‐sized testes of 1.2 g or more. When the extent of testicular alterations was estimated in sections for light microscopy by use of a semiquantitative testicular biopsy score count (TBSC), the morphology of the testes corresponded closely to the testis weight (r = .94), small testes having correspondingly low TBSC scores. In severely altered small testes, the seminiferous tubules were narrower than in sham‐operated rats, and numbers of germ cells were greatly depleted. Many tubules contained only Sertoli cells and spermatogonia, although spermatocytes were present in a minority of tubules. A few seminiferous tubules contained multinucleate spermatids. Electron microscopy of severely altered tubules revealed closely apposed processes of Sertoli cells, which contained filaments, microtubules, and endoplasmic reticulum. In contrast, testes with normal weight in vasectomy and vasovasostomy groups resembled those of the sham‐operated animals. Comparison of distributions of testicular biopsy score counts demonstrated differences between vasectomy and vasovasostomy groups as time after operation increased. At the 3–4‐month intervals, approximately one‐third of the testes were severely altered in both vasectomy and vasovasostomy groups. However, by 7 months the proportion of altered testes progressed to 60% in animals with a vasectomy, while it remained similar to the earlier intervals in rats that had received a vasovasostomy. These results suggest that vasovasostomy may prevent the progression of testicular alterations that occur after vasectomy, but vasovasostomy does not appear effective in reversing testicular changes.
Retinal cell death occurs in the absence of retinal disc invagination: Experimental evidence in papaverine‐treated chicken embryos
Authors: García‐Porrero Juan A. , Colvee Elvira , Ojeda Jose L. 
Published: February 2005

AbstractIn an attempt to clarify the relationship between the presence of retinal cell death and the invagination of the optic vesicle, we have tested the occurrence and cytological characteristics of the retinal necrotic areas in the embryonic chicken after the administration in ovo of papaverine. Papaverine, a Ca2+ antagonist, was found to prevent the invagination of the optic vesicle. All embryonic retinae presented two distinct necrotic areas. However, these areas of cell death appeared abnormally located in the experimental, uninvaginated retina. One area was located at the transition between the retinal disc and the ventral wall of the optic vesicle; a second area was located in the dorsal wall of the optic vesicle, close to the optic stalk. We suggest that these necrotic areas represent the normal necrotic areas, should the invagination of the retinal disc have taken place. Retinal cell death appears to beprogrammed; it occurs whether the retinal disc invaginates or not. Cell death appears, in this experimental model, as a natural marker giving evidence that the embryonic retinal cells move from the optic stalk into the invagination retinal disc during normal eye cup formation.In addition to the uninvaginated optic vesicle the lens placode failed to invaginate in 45% of the cases, forming a lens vesicle in 55% of the remaining cases. This suggests that the two processes of invaginate in 45% of the cases, forming a lens vesicle in 55% of the remaining cases. This suggests that the two processes of invagination are governed by a different set of factors.
Thin collagenous septa in cardiac muscle
Authors: Dolber Paul C. , Spach Madison S. 
Published: February 2005

AbstractLight and electron microscopy were used to study the structure and distribution of thin collagenous septa (sheets) in dog and rabbit cardiac muscle to determine whether they, like thick collagenous septa, could affect electrical impulse propagation. Generally, thin septa (0.2–0.5 μm) ensheathed myocytes or groups of myocytes for short distances and thicker septa partially or completely ensheathed groups of myocytes for long distances (up to several mm); together, thin, and thick septa divided the myocardial mass into myocyte cords (funicles) of 10–30 μm diameter. Septal architecture varied not only between regions and within regions at different ages but also within single bundles, precluding the assumption that the architecture found in one bundle can be applied to another. Electron microscopy demonstrated that thick septa consisted of many tightly packed collagen fibrils, often with distinct layers running at different angles; thin septa consisting largely of circumferential collagen fibrils. Thin septa in dog ventricular papillary muscle generally contained few and widely spaced collagen fibrils, whereas thin septa in dog atrial Bachmann's bundle contained tightly packed collagen fibrils. In either site, thin septa were rarely breached by nexuses and thus marked sites where lateral intercellular electrical coupling was unlikely. Serial 7 μm cross sections of dog Bachmann's bundle stained by a modification of the picrosirius red technique showed that thin septa sometimes persisted uninterrupted over several myocyte lengths. The results provide evidence that thin septa comprimised of tightly packed collagen fibrils may significantly modify impulse propagation transverse to the longitudinal axis of the myocytes.
Morphology and endocrine production of cells in the islets of langerhans of the Chacma baboon
Authors: Wolfe‐Coote Sonia A. , du Toit D. F. 
Published: February 2005

AbstractBiopsies of the pancreas head, tail, and uncinate regions of 6 Chacma baboons (Papio ursinus) were processed for ultrastructural and immunocytochemical (ICC) studies using avidin‐biotin peroxidase label for light microscopy (LM) and immunogold for electron microscopy (EM). Survey 0.5 μm sections of Spurrs resin embedded tissue revealed areas of suitable islets. Thin 100‐nm sections were then cut and stained from the osmicated blocks for ultrastructural studies. For ICC investigations, 1 μm sections were immunolabeled for LM before areas were selected for thin sectioning for ultrastructural immunolabeling.The baboon endocrine pancreas ultrastructure was found to be similar to that of other mammals with minor differences in islet and secretory granule size and shape and in electron opacity of the secretory granule cores. Insulin glucagon, somatostatin and pancreatic polypeptide (PP) producing cells were described. A small number of cells were seen to contain both glucagon and PP and some D cells were observed to contain a few granules with both the appearance and immunoreactivity of A cell secretory granules.Statistical analysis of 100 secretory granule diameters of each of the 4 cell types in 6 baboons revealed significant differences (p < 0.001) in size between all but those of the A and D cells.The insulin precursor subunit, C‐peptide, and the glucagon precursor, glicentin, were each found together with the final hormone product in their respective secretory granules. The precursors were often located toward the periphery of the secretory granule, suggesting that the conversion of precursor to active hormone may be membrane associated.A nonrandom topographical association was observed between A and D cells, suggesting a strong functional implication.
Demonstration of expanding cell populations in mouse pancreatic acini and islets
Authors: Tsubouchi Susumu , Kano Eiichi , Suzuki Harumi 
Published: February 2005

AbstractThe acinar and islet cells of the adult mouse pancreas were examined by radioautography after continuous infusion of 3H‐thymidine, for periods varying from 1 to 60 days, to determine whether they behaved like renewing or expanding cell populations. The labeling of both cell types increased with the duration of the continuous infusion and reached 2.22% and 12.0%, respectively, after 60 days. The rate of acinar and islet cell labeling was estimated from the regression line of the labeling index versus time and given as 0.039% and 0.20% cells per day, respectively.The rate of cell labeling was relatively low in these acinar and islet cells in comparison to the relatively high rate in duct cells. Occasionally, acinar cell labeling was not uniform, showing high labeling in the outer peripheral region of a lobe and at the periphery of the islets. Both acinar and islet cells increased in number in the adult, and at a rate indicating they are expanding cell populations. Their doubling times were estimated as 2,564 days (7.0 years) and 500 days (1.3 years), respectively. Duct epithelial cell populations were dividing at a rate indicating that they are renewing cell populations.
Quantitative ultrastructure of histochemically identified avian skeletal muscle fiber types
Authors: Hikida Robert S. 
Published: February 2005

AbstractA cryostat retrieval method and combined adenosine triphosphatase (ATPase) and acetylcholinesterase (AChase) method were used to study the ultrastructure and innervation of histochemically identified skeletal muscle fibers in different pigeon muscles. The Z‐line structure and volume percentage sarcotubular system were analyzed from different muscles selected for their composition by fiber type. Histochemically, three main fiber types were investigated: slow tonic fibers with a moderate ATPase activity after preincubation at acid or alkaline pH; fast‐twitch fibers that had high activity after alkaline treatment and low activity after acid preincubation; and a type considered to be slow‐twitch that had low activity after alkaline, and high after acid preincubation. Both the slow tonic and slow‐twitch fibers had multiple, en grappe innervation, while the fast‐twitch fibers had robust, single end plates. The Z‐line of the fast‐twitch and slow‐twitch fibers had a regular square lattice pattern, in contrast to the granular, nonlattice structure of the slow tonic Z‐line. The volume percentage sarcotubular system of the slow‐twitch fibers was intermediate between and significantly different from that of the fast‐twitch and slow tonic fibers. These correlative analyses suggest that the avian muscles contain not only the fast‐twitch and slow tonic fibers previously known, but also a slow‐twitch fiber that appears to be intermediate between the tonic and the mammalian slow‐twitch fiber type. Based on the abundance of the sarcotubular system, this fiber type appears to be fast‐contracting and ‐relaxing, in spite of being multiply innervated.
Histochemical and elemental localization of calcium in the granular cell subapical granules of the amphibian urinary bladder epithelium
Authors: Davis Walter L. , Jones Ruth Gwendolyn , Hagler H. K. , Farmer Gene R. , Goodman David B. P. 
Published: February 2005

AbstractThe ultrahistochemical analysis of apical granules in the epithelial cells, i.e., granular cells, of the amphibian urnary bladder using the N,N‐naphthal‐oylhydroxylamine procedure identified the presence of calcium in these structures. Subsequent analytical microscopy employing fresh‐frozen ultrathin cryosections for X‐ray microanalysis of the granules further confirmed the above histochemical findings. In addition to calcium, elemental analysis indicated the presence of magnesium, phosphorus, sulfur, silicon, potassium, and chlorine either within or in close proximity to the granules. The possibility that these granules function as subcellular compartments for the uptake and storage of calcium ions, in a way similar to mitochondria, and thus function in intracellular calcium homeostasis, is discussed. Additionally, a role for this cation in the secretion of granular glycoproteins, i.e., stimulus‐secretion coupling, is hypothesized.
Systematic distribution of muscle fiber types in the medical gastrocnemius of the laboratory mouse: A morphometric analysis
Authors: Brasseur Jeannette E. , Curtis Robin L. , Mellender James W. , Rimm Alfred A. , Melvin John L. , Sulaiman A. R. 
Published: February 2005

AbstractMidbelly cross sections of the medial gastrocnemius muscle of young adult male laboratory mice were subjected to ATPase histochemistry with preincubation at pH 4.6. Through the use of a sampling grid and computer‐assisted morphometric analysis, 26 to 35% of the total muscle fibers were sampled and classified as type I, IIa, or IIb.Photomicrographs (16×20 in.) of five muscles were divided into octants according to a standardized procedure. Total fiber counts and percent of fibers sampled were determined. Variability of sample size per octant was noted, but when averaged across entire muscles, it was in all instances greater than 33%. Fiber type frequency per octant was tested for goodness of fit to a random model by means of a chi‐square statistic for equal expected frequencies. Deviation from random fiber type frequency was significant at the P = 0.001 level for every muscle. More importantly, when these data were pooled and again tested using the same method, the probability estimate was less than P = 0.001. This established that the variations in the fiber type proportions found in each mouse followed a common pattern.The systematic fiber type distribution confirmed by these morphometric and statistical methods supports the impression expressed by many muscle biologists that this muscle displays a consistent and complex intramuscular organization.
Improved ultrastructural preservation of epiphyseal chondrocytes by the freeze‐substitution method
Authors: Akisaka Toshitaka , Subita Gus Permana , Kawaguchi Hiroyuki , Shigenaga Yoshio 
Published: February 2005

AbstractThe ultrastructure of epiphyseal chondrocytes was studied following quick‐freezing and freeze‐substitution, and was compared to that of cells fixed with aqueous aldehydes. The former approach provided an improved ultrastructural preservation whereby every type of chondrocyte exhibited a smoother cell contour. The plasma membrane as well as intracytoplasmic membranes revealed a trilaminar substructure. The intracytoplasmic ground substance was composed of flocculent materials which were in direct contact with the inner leaflet of the plasma membrane. Within the extracellular matrix the proteoglycan network adhered to the outer leaflet of the plasma membrane. Whenever cellular shrinkage took place, the flocculent matrix within the cytoplasm and the proteoglycan network in the pericellular matrix disappeared. The contents of the RER, the Golgi apparatus, and the intracellular vesicles and vacuoles were well retained. In the proliferative zone, the Golgi saccules of young cells contained a thread‐like structure showing a clear periodicity. The cytoplasmic vesicles and vacuoles showed marked variation in their electron density. Intramitochondrial granules were sensitive to aqueous treatments, as evidenced by the observation that they disappeared after either floating on water or staining with aqueous solution. In the calcifying zone, mitochondrial granules were noted within hypertrophic chondrocytes, a feature that was not observed following conventional processing. Cytoskeletal elements were well preserved in all types of cells. A dense microfilamentous network occupied the pericellular cytoplasm. Bundles of microfilaments were seen in the cellular peripheral processes. Microtubules were distributed throughout the cytoplasm, and the Golgi complex was intimately associated with the microtubule network; it appears that the secretory processes are involved with the microtubules.
Development of preimplantation rabbit embryos after in‐vitro culture and embryo transfer: An electron microscopic study
Authors: Hegele‐Hartung Christa , Fischer Bernd , Beier Henning M. 
Published: February 2005

AbstractCompared to in vivo development, in vitro culture of mammalian embryos results in developmental retardation. To study the potential of reversibility of growth retardation we investigated ultrastructurally day 3 rabbit embryos after 1 day in vitro, and cultured embryos that were transferred after culture into recipient rabbits for 1 day. Morphology was compared with ultrastructure of noncultured controls. The noncultured embryos were compacted morulae; the characteristic ultrastructure is described in detail. After 1 day in culture, morulae had developed into early blastocysts. However, unlike the results in vivo, expansion of the blastocysts did not occur and some of the cultured embryos developed trophoblast herniations. In all cultured embryos morphological signs of degeneration were seen with swollen mitochondria, with a dense, granular appearance of the cytoplasm, and with an increase in number of lysosomes. Transfer of cultured blastocysts into uteri of day 3 pseudopregnant recipients resulted in ultrastructurally intact and expanded blastocysts. Transfer into uteri of day 4 pseudopregnant recipients and into uteri of nonpregnant recipients, however, did not yield reversibility of the unphysiological features suffered during the previous time in culture. Although blastocysts were well expanded, distinct signs of injury to the blastomeres were present, proceeding from loss of complete blastomeres to structural changes such as large lamellar structures, dilation of smooth endoplasmic reticulum and Golgi complexes, and clumping of mitochondria. We conclude that developmental retardation during in vitro culture is accompanied by distinct morphological changes. As soon as 24 hr after transfer, these changes can be reversed. This compensation, however, is achieved only if embryos are transferred into recipients that are adapted to the embryo's developmental stage, which is not identical to the embryo's chronological age. Our findings demonstrate that the period of 24 hr of in vitro development matches only a few hours of in vivo development.
Changes in the distribution of microtubules and intermediate filaments in mammalian Sertoli cells during spermatogenesis
Authors: Amlani S. , Vogl A. W. 
Published: February 2005

AbstractWe have studied the distribution of microtubules and intermediate filaments in mammalian Sertoli cells during spermatogenesis. The arrangement of microtubules was determined, by indirect immunofluorescence, in ground squirrel testes that were (1) fixed, mechanically fragmented, and attached to polylysine‐coated slides, and (2) fixed, embedded in polyethylene glycol, and sectioned. Intermediate filament patterns were determined, also by indirect immunofluorescence, in sections of unfixed rat testis. Results from these studies were confirmed and extended using electron microscopy.Microtubules first become evident in lateral processes that embrace round spermatids. When spermatids elongate and become situated in apical crypts of Sertoli cells, the microtubules become oriented parallel to the long axis of Sertoli cells and surround the crypts. As spermatids mature and acquire a saucer shape, apical microtubules progressively concentrate in Sertoli cell regions adjacent to the acrosome and eventually form discrete C‐shaped structures that disappear during spermiation.Intermediate filaments in rat Sertoli cells are centered around the nucleus. From perinuclear regions, filaments extend toward desmosome‐like junctions with early spermatogenic cells and into the apical cytoplasm where they have a transient association with crypts containing elongate spermatids. Filaments amongst crypts are most evident in early stages of the spermatogenic cycle when apical crypts are situated deep within the epithelium. They become less evident and eventually disappear as spermatids assume a more apical position. Our fluorescence studies and ultrastructural analyses indicate that the association of intermediate filaments with crypts is specific to regions adjacent to the dorsal or convex aspect of spermatid heads. In these regions, approximately 8 to 12 uniformly aligned filaments are intimately associated with actin filaments in ectoplasmic specializations surrounding the crypts.We conclude that, like actin, the distribution of microtubules and intermediate filaments changes in Sertoli cells during spermatogenesis. The distribution of microtubules correlates with the irregular columnar shape of Sertoli cells. We suspect that the apically situated intermediate filaments may play a role in anchoring or positioning Sertoli cell crypts deep within the epithelium during the early stages of the spermatogenic cycle.