bluuebunny/crossref_metadata_2025_split huggingface dataset:
Structural features of the apical and tubulovesicular membranes of rodent small intestinal tuft cells
Authors: Trier Jerry S. , Allan Carol H. , Marcial Manuel A. , Madara James L. 
Published: February 2005

AbstractTuft cells are present in most columnar epithelia derived from endoderm including the small intestine. They are characterized by long, wide apical microvilli and an extensively developed cytoplasmic tubulovesicular system. We examined in detail the structural features of the apical plasma membrane of small intestinal tuft cells from adult guinea pigs, rats, and adult and suckling mice with freeze‐fracture and conventional transmission electron microscopy methods and utilized cationized ferritin and horseradish peroxidase as tracers to determine whether tuft cells endocytose macromolecules. The microvillus membrane of intestinal tuft cells has few P‐face intramembrane particles, displays little alkaline phosphatase activity, and is highly enriched in cholesterol. Tuft cell tight junctions resemble those of absorptive cells in strand count and strand‐to‐strand crosslinks but, unlike those of absorptive cells, they display many abluminal free‐ending strands. Tuft cells of adult and suckling mouse intestine show no evidence of internalization of cationized ferritin or, in suckling mice, uptake of horseradish peroxidase. We conclude that the microvillus membrane of small intestinal tuft cells is protein poor but cholesterol‐rich and that small intestinal tuft cells do not endocytose macromolecules in bulk from the intestinal lumen.
Isolation and cytochemical characterization of globule leukocytes from rat tracheal epithelium
Authors: Baert Johan 
Published: February 2005

AbstractGlobule leukocytes, dispersed throughout the respiratory epithelium as single cells, were isolated from rat trachea and were enriched by centrifugation on a discontinuous Percoll gradient. The isolation and enrichment procedure yields a cell fraction containing 75% globule leukocytes. The cell viability, as assessed by trypan blue exclusion, was at least 98%. Cells were maintained in short‐term culture without apparent loss of viability and enzyme activity. The isolated globule leukocytes seem not to express significant levels of cytotoxicity against 51Cr‐labeled YAC‐1 target cells. In fixed cytocentrifuge smears, globule leukocytes appear as more or less rounded to oval cells with a low nucleo‐cytoplasmic ratio and with a mostly eccentrically located nucleus. Characteristic intracytoplasmic granules are stained with toluidine blue, alcian blue, and May‐Grünwald‐Giemsa stains. The applied cytochemical methods demonstrate that tracheal globule leukocytes are stained for alpha naphthyl acetate esterase and naphthol‐AS‐D‐chloroacetate esterase, but not for alpha naphthyl butyrate esterase, N‐acetyl‐DL‐phenylalanine‐B‐naphthyl esterase, and endogenous peroxidase. Isolated rat peritoneal cells were used as positive control cells for the cytochemical reactions. The obtained cytochemical profile of tracheal globule leukocytes is compared to the known cytochemical profile of intestinal globule leukocytes and large granular lymphocytes. The cytochemical dissimilarities between tracheal and intestinal globule leukocytes may suggst that both kinds of globule leukocytes represent a different form of the same cell type or even different cell types.The cytochemical pattern of tracheal globule leukocytes is closely related to that of large granular lymphocytes, which have been postulated as a possible source for globule leukocytes.
Application of the fiber‐optic perfusion fluorometer to absorption and exsorption studies in hairless mouse skin
Authors: Shackleford John M. , Yielding K. Lemone 
Published: February 2005

AbstractThis study was undertaken to test the fiber‐optic perfusion fluorometer as a direct means of evaluating skin absorption and exsorption in hairless mice. Skin‐barrier compromise was accomplished in the absorption experiments by application of dimethyl sulfoxide to the skin surface or by partial removal of the stratum corneum with sticky tape. Absorbed fluorescein was measured easily in unanesthetized control (skin‐barrier intact) and experimental mice. Unabsorbed chemical did not fluoresce 15 minutes after application, although it was present on the surface of the skin as a dry powder. The time course of fluorescein elimination from the skin was related to a rapid phase (vascular removal) and a slow phase (reservoir entrapment).In the exsorption experiments the fluorescein was injected intraperitoneally. Back skin on the right side was swabbed with either dimethyl sulfoxide or 1% capsaicin in alcohol prior to the injections, and differences in skin fluorescence on the left (control) and right sides were recorded. One application of dimethyl sulfoxide or capsaicin increased the level of skin exsorption. Three applications of dimethyl sulfoxide almost doubled the amount of exsorbed dye, whereas three applications of the capsaicin inhibited the exsorption process.It was concluded that the fiber‐optic perfusion fluorometer provides an excellent technique in support of other methods of investigating the skin.
Exposure to formaldehyde in anatomy: An occupational health hazard?
Authors: Pabst Reinhard 
Published: February 2005

AbstractThe adverse effects of formaldehyde have been discussed very emotionally in public. Anatomists, technicians in histology and embalming laboratories, as well as medical students during their dissection course are all exposed to formaldehyde, which in many situations crosses the threshold for irritation of the eyes and upper respiratory tract. There is no doubt about the acute toxic effects and the occurrence of contact dermatitis caused by formaldehyde. Studies in rats and mice using high concentrations over an extremely long period (which would not be tolerated by humans) resulted in squamous carcinoma of the nose. Epidemiologic studies on the mortality of medical personnel exposed to formaldehyde do not provide sufficient evidence of cancerogenicity. A number of recommendations will be given for defining the exact concentration in a dissecting room or laboratory and for ways of reducing formaldehyde concentrations and thus minimizing adverse health hazards. These data could initiate a discussion among anatomists, and with technicians and students, based on a sound scientific background rather than on emotion.
The effects of cholesterol depletion on cellular morphology
Authors: De Pace Dennis M. , Esfahani Mojtaba 
Published: February 2005

AbstractCells of the U937 cell line were grown in delipidated calf serum for 24 and 48 hr. These cells are known cholesterol auxotrophs. When grown for 48 hr without an exogenous source of cholesterol, these cells are known to become depleted of their intracellular cholesterol stores by greater than 95%. The result is an aggregation of the cells upon mild agitation of the culture. Examination of the cell aggregate from these cultures revealed cells in various stages of altered morphology. There was a loss of microvilli from the cells. Subsequently, the Golgi complex became dilated, and secondary lysosomes and myelin figures accumulated in the cytoplasm. The cells became swollen, and the rough endoplasmic reticulum became dilated. A small percentage of the cells showed complete disintegration, with release of membrane‐bound fragments and other intercellular debris. These events suggest that the depletion of cholesterol results in the inability of the cell to produce usable membrane. As a consequence, the synthetic apparatus of the cell becomes disrupted.
Microtubules, intermediate filaments, and actin filaments in the odontoblast of rat incisor
Authors: Nishikawa Sumio , Kitamura Hironori 
Published: February 2005

AbstractActin filaments, intermediate filaments, and microtubules in the odontoblasts of rat incisors were investigated electron microscopically using heavy meromyosin and taxol. Actin filaments were abundant at the periphery of the odontoblast process in the form of a network or in bundles. In a branch of the odontoblast process, longitudinally oriented actin filament bundles were found. Most actin filaments were associated with the plasma membrane via electron‐dense material which stained with tannic acid. The intermediate filaments had a diameter of 11 to 13 nm. They were distributed throughout the cytoplasm of odontoblasts. They ran lengthwise in the core of the odontoblast process, which showed a different distribution compared with that of actin filaments. Microtubules, which were disrupted after Triton X‐100 but preserved by addition of taxol, tended to be associated with intermediate filaments. Such a relation was also seen in conventional preparations. Coated vesicles, which were abundant at the periphery of the odontoblast process, were often associated with actin filaments. Therefore, it is suggested that actin filaments, in the odontoblast process at least, play a role associated with the coated vesicles at the periphery of the process, and may be involved in coated vesicle transport.
Early stages of development in the caudal neural tube of the golden syrian hamster (Mesocricetus auratus)
Authors: Shedden Peter M. , Wiley Michael J. 
Published: February 2005

AbstractSecondary neurulation is the morphogenetic process whereby the caudal segments of the neural tube are derived from cells in the embryonic tail bud. Comparative studies have demonstrated similar characteristics in the mechanism of secondary neurulation among tailless species, which are thought to be due to the evolutionary reduction in tail length (Hughes and Freeman, 1974). In order to explore this hypothesis further, light and scanning electron microscopy was used to study early stages of neurulation in the tail buds of hamster embryos. The golden Syrian hamster is a relatively common laboratory rodent with a reduced tail. In this species, secondary neurulation first became apparent in embryos with approximately 17 pairs of somites. This was well before closure of the posterior neuropore which occurred at the 21‐somite stage. The lumen of the neural tube appeared to extend into the tail bud in an even and progressive fashion accompanied by reorientation and rearrangement of tail‐bud cells. The mechanism appeared to be similar to that reported in long‐tailed rodents.
Electron microscopic and autoradiographic characterization of hindlimb muscle regeneration in the mdx mouse
Authors: Anderson J. E. , Ovalle W. K. , Bressler B. H. 
Published: February 2005

AbstractThe pattern of postnatal growth and development of skeletal muscle in mdx mice was studied by light and transmission electron microscopy and by autoradiography and was compared with that in their normal age‐matched controls at 4 and 32 weeks of age. The muscle weights of both the extensor digitorum longus (EDL) and soleus muscles of mdx mice were significantly greater than those in control mice at both ages. Body weights of male and female mdx mice were also increased over controls up to 12 weeks of age. At 4 weeks, both the EDL and soleus muscles exhibited focal areas of degeneration, necrosis; and regeneration of centrally nucleated extrafusal fibers resulting in a wide range of fiber sizes. By 32 weeks, the majority of fibers in both muscles were centrally nucleated, and focal areas of recent regeneration were observed. By electron microscopy, the course of macrophage infiltration into areas of degenerating fibers and the ongoing regeneration of myofibers within redundant cylinders of external lamina were noted. This pattern was frequent in 4‐week‐old mdx muscles and was present to a lesser degree at 32 weeks. A notable lack of both adipose tissue infiltration and fibrotic change in the endomysium were observed in muscles at both ages. Autoradiograms of muscles from 4‐week‐old mdx mice injected with tritiated thymidine showed an increased proportion of labeled sublaminal nuclei at 24 and 48 hours after injection compared to controls. At 32 weeks of age, labeling of nuclei in muscles of mdx mice was also greater than in controls, but was reduced compared to muscle labeling in 4‐week‐old mdx mice. The observed features of mdx muscle tissue suggest that this animal model is more applicable to the study of regeneration dynamics than to Duchenne‐type human muscular dystrophy.
Ultrastructural studies of bovine retinal microvascular basement membranes with the cationic dye ruthenium red
Authors: Schmidley James W. 
Published: February 2005

AbstractOur recent observation that the basement membranes of brain microvessels do not stain with the cationic dye ruthenium red has raised the question of whether the basement membranes of this and other vascular beds functioning as barriers between blood and neural tissues are deficient in the polyanionic macromolecules, such as glycosaminoglycans, which are responsible for the ruthenium red staining of other vascular basement membranes. We therefore attempted to produce staining in the only barrier‐type microvascular basement membrane known to contain heparan sulfate. Bovine retinas were fixed by immersion in aldehyde fixatives containing ruthenium red, buffered with either 10 mM or 100 mM sodium cacodylate. We found discrete, electron‐dense deposits of ruthenium red in vascular basement membranes, quite similar to those seen in vascular basement membranes of nonneural tissues after exposure to ruthenium red. These deposits were more distinct and more frequent in tissue exposed to ruthenium red–aldehyde solutions buffered with 10 mM cacodylate. They were not seen if ruthenium red was omitted from the fixative. The results demonstrate that anionic macromolecules in basement membranes of barrier‐type microvessels can be stained with cationic dyes, and suggest that the failure of brain microvessels to stain with ruthenium red may be the result of a relative or total lack of polyanion in this basement membrane, or of other unique properties.
Anatomical observation of six calves affected with segmental aplasia of the spinal cord
Authors: Hiraga Takeo , Abe Mitsuo 
Published: February 2005

AbstractFour male and two female Holstein‐Friesian calves with segmental aplasia of the spinal cord were examined macroscopically and radiographically, and in some cases also histologically. External symptoms included inability to stand, deep depression of the body near the middle of the back but without any blemish in the skin, and slight reduction of the body length. Both hind limbs were almost normal. In every case segmental aplasia of the spinal cord was observed between the caudal thoracic and the cranial lumbar region. Owing to this defect, the vertebrae of that limited area consisted only of the body and the ribs fused on both sides. The sternum showed abnormal ossification at its caudal part. Other defects were observed such as kyphoscoliosis (six cases), polycystic kidney (one case), cryptorchidism (one case), and XX/XY chimerism (one case). From these findings it was apparent that this anomaly was uniquely different from the other two main spinal cord anomalies, spina bifida and perosomus elumbis. One conceivable pathogenesis of this rare anomaly, it was conjectured, is as follows: This anomaly results primarily from a segmental disorder of the neural tube, probably due to vascular problems, whereby a part of the spinal cord fails to develop properly from its normal genesis. Anomalous shapes of the vertebral column and ribs are perhaps secondary defects caused by aplasia of the spinal cord.
Coordinated three‐dimensional reconstruction from serial sections at macroscopic and microscopic levels of resolution: The human heart
Authors: McLean Miriam R. , Prothero John 
Published: February 2005

AbstractThis report describes procedures we have developed for obtaining correlated quantitative structural information at two very different levels of resolution. Accurate reconstructions of entire organs and samples of tissue within organs were produced in correct scalar and topographical relationship using computer‐assisted techniques. A specially designed sectioning apparatus, a macrovibratome, was used to section serially the ventricles of the human heart macroscopically. Photographs were taken of every slice. A tissue block excised from a slice at a specified locus in the left ventricular wall was embedded in plastic; serial‐3 μm sections were cut in each of two orthogonal orientations. Photomicrographs were taken by semi‐automated microscopy. Images of both macroscopic and microscopic sections were projected onto a bitpad and manually digitized. The resulting tables of x‐, y‐, and z‐coordinates were reassembled on a VAX 11/750 computer, then transferred to a high‐performance graphics workstation and displayed as three‐dimensional images. Microscopic images were shown in the correct reference frame with respect to the macroscopic (parent) structure.
EHDP‐induced rachitic syndrome in rats is not reversed by vitamin D metabolites
Authors: Atkin Isaac , Ornoy Asher , Pita Julio C. , Muniz Ofelia E. , Agundez Agueda , Castiglione Greg , Howell David S. 
Published: February 2005

AbstractTo examine whether either of the two known active vitamin D metabolites 1,25(OH)2D3 or 24,25(OH)2D3 could reverse the mineralization defect induced by 1‐hydroxyethylidene‐1,1‐bis phosphonate (EHDP), a model of EHDP‐induced rickets was used. Rats at the age of 31 days were injected for 10 consecutive days with EHDP (10 mg/kg). Other littermates were treated with a combination of EHDP and either 1,25(OH)2D3 or 24,25(OH)2D3 or were treated following 10 days of EHDP, with either of the vitamin D metabolites for an additional 72 hr. Samples of cartilage fluid (Cfl) and of blood were removed prior to sacrifice for biochemical studies of some parameters of calcification. These parameters were correlated with the results of light and electron microscope studies of growth plate cartilage and bone. EHDP‐treated rats revealed signs of typical rickets, manifested by widened growth plates and impaired bone mineralization. Transmission electron microscope (TEM) examination revealed matrix vesicles distributed throughout the growth plate; however, there appeared to be an arrest of the spread of the crystals at the provisional zone of calcification. Treatment with either 1,25(OH)2D3 or 24,25(OH)2D3 failed to reverse the rachitic condition of the animals. Serum calcium blood levels were elevated in the 1,25(OH)2D3 and EHDP‐treated group. 1,25(OH)2D3 and 24,25(OH)2D3 further increased the already elevated serum alkaline phosphatase levels observed in EHDP rats, although the increase observed with 1,25(OH)2D3 was not statistically significant. In contrast to this, 24,25(OH)2D3 lowered the Cfl levels of alkaline phosphatase to the normal range despite the absence of apparent morpholoogical healing of the EHDP rachitic condition. It therefore appears that in our animal model pharmacological doses of vitamin D metabolites do not reverse the EHDP‐induced mineralization defect.
The ductuli efferentes of the goat: A morphological study
Authors: Goyal Hari O. , Williams Carol S. 
Published: February 2005

AbstractThe morphology of the ductuli efferentes of the goat was compared with that of other animal species, especially with that of the bull. Both in the goat and in the bull, it forms a slightly brownish, bulbous mass of highly convoluted ductules (18–19 in the goat, 13–16 in the bull) that occupies approximately one third of the first limb of the caput epididymidis. The epithelium consists of two major cell types, ciliated and nonciliated, and a few intraepithelial lymphocytes and macrophages. The nonciliated cells can be further divided into three types: type II cells are characterized by specific granules that are dense, mostly homogeneous, eosinophilic, osmiophilic, and positive to periodic acid‐Schiff (PAS) staining; type III cells are characterized by specific vacuoles that appear empty and do not stain with PAS, eosin, or osmium; type I cells lack both granules and vacuoles. These morphological, histochemical, and tinctorial differences observed among nonciliated cell types suggest that they are probably independent cell types rather than functional stages of one cell type. All three cell types are endowed with absorptive features such as microvilli, pinocytotic vesicles, and subapical vacuoles, but a higher differentiation of these features in type III cells suggests their greater role in the absorption of testicular fluid.Whether granules of type II cells and vaculoes of type III cells are absorptive and/or secretory remains unresolved from the available data. However, some circumstantial evidence, as presented in the discussion, supports the latter possibility.
Ontogeny of immunoreactive calcitonin gene‐related peptide in thyroid C cells from dogs, rabbits, and guinea pigs
Authors: Kameda Yoko 
Published: February 2005

AbstractOntogeny of immunoreactive calcitonin gene‐related peptide (CGRP) in thyroid C cells of dogs, rabbits, and guinea pigs from early fetuses to adults was investigated by an immunoperoxidase method, in comparison with the development of immunoreactive calcitonin and somatostatin. The presence of immunoreactive CGRP in mature C cells was different from species to species. Dog and rabbit C cells revealed intense immunoreactivity for CGRP, whereas guinea pig C cells revealed very weak immunoreactivity or none. In dog fetuses, the appearance of immunoreactive CGRP was early. At around 35 days of gestation, when the follicular cells were not yet organized into follicles, immunoreactivities for three peptides—calcitonin, somatostatin, and CGRP—began to appear in C cells. While the highest population of somatostatin‐positive cells was attained when the primordial follicles were vigorously formed throughout whole thyroid parenchyma and their frequency progressively declined thereafter, CGRP‐positive cells as well as calcitonin‐positive cells gradually increased in number and intensity with gestational age. The developmental pattern of immunoreactive CGRP coincided with that of immunoreactive calcitonin in dog C cells. In rabbit fetuses, at 25 days of gestation, when thyroid follicles stored large amounts of colloid and C cells already exhibited intense immunoreactivity for calcitonin, CGRP immunoreactivity as well as somatostatin immunoreactivity began to appear. Subsequently, immunoreactivities for the three peptides gradually increased with age, although calcitonin immunoreactivity was outstandingly intense among them. In guinea pig C cells, intense immunoreactivity for CGRP was not observed in any stages or development. These results indicate that there are developmental profiles of CGRP characteristic for each animal, and the ratio of CGRP and calcitonin produced from calcitonin genes in C cells seems to be fixed for life.