bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of paraformaldehyde fixation on localization and characterization of insulin‐like growth factor‐I (IGF‐I) receptors in the rat brain
Authors: King Michael G. , Baskin Denis G. 
Published: May 2005

AbstractIn order to design an approach for localizing IGF‐I receptors within the intact CNS, the effect of paraformaldehyde (PAF) fixation on receptor binding was examined. Cryostat sections of rat brains, which were perfused with O to 10% PAF, were incubated in 125I‐IGF‐I and assayed for binding under equilibrium conditions. Binding was quantified from 10 brain regions, involving laminae and nuclei from median eminence, thalamus, hippocampus, choroid plexus, pyriform cortex, and cerebral cortex, by computer densitometry of film autoradiographs. The specific binding, saturation curves, Bmax and Ka, ligand specificity, and binding reversibility of IGF‐I binding sites were not significantly affected by 1% or 2% PAF. However, 4% PAF elevated IGF‐I receptor total binding, nonspecific binding, and Ka, and decreased Bmax, presumably by increasing the number of tissue‐receptor interconnections, Only nonspecific 125I‐IGF‐I binding persisted when 10% PAF was used. These results indicate that tissue perfused with 2% PAF can be used for localizing IGF‐I receptors by autoradiographic binding methods.
Medial nucleus of the amygdala in the adult Syrian hamster: A quantitative Golgi analysis of gonadal hormonal regulation of neuronal morphology
Authors: Gomez Diana M. , Newman Sarah Winans 
Published: May 2005

AbstractThe medial nucleus of the amygdala (Me) processes both chemosensory and hormonal input. In the male Syrian hamster the integrity of this nucleus is essential for normal reproductive behavior. To determine if gonadal steroids modulate neuronal structure in this nucleus, the morphology of Golgi‐stained neurons in the anterior and posterior regions of Me were compared in castrated and reproductively intact adult hamsters.In castrated males, neurons in the posterior, but not the anterior, region of Me undergo structural changes, as indicated by a decrease in the mean highest dendritic branch level and mean somal area compared to intact males. To further elucidate the importance of testosterone and its metabolites in maintenance of neuronal structure in the adult, seven groups of male Syrian hamsters were studied. Animals were castrated and received a blank silastic capsule or a capsule filled with either testosterone, dihydrotestosterone, or estradiol. or two capsules containing both metabolites, dihydrotestosterone and estradiol. Two groups of reproductively intact animals were included: brains from one group were processed simultaneously with the castrated and hormone‐treated groups (control intact group), and the other group was processed at the beginning of the experiment. Animals were tested for mating behavior and flank glands were measured to test whether the capsules were effective in releasing the hormones into circulation. After a 12‐week survival period, the brains were processed with Golgi stain and well‐impregnated neurons from the posterior Me were quantitatively analyzed for somal area, highest dendritic branch, total dendritic length, and density of spines. All the measures analyzed revealed a consistent pattern of response to the different gonadal steroids. Castration resulted in a decrease in the mean somal area, the mean highest dendritic branch, and the percentage of neurons with tertiary branch segments. Dihydrotestosterone treatment also resulted in a significant decrease in somal area, mean highest dendritic branch, and percentage of neurons with tertiary dendritic branches. In addition, the total dendritic length and spine density on terminal dendrites were reduced in these brains. The remaining hormone treatment groups were not significantly different from the control group. These results suggest that in orchidectomized male Syrian hamsters, testosterone or its aromatized form, estradiol, but not dihydrotestosterone, is sufficient to maintain the normal morphology of the neurons in the posterior part of the medial nucleus of the amygdala.
Dendritic and synaptic properties of collicular neurons: A quantitative light and electron microscopical study of Golgi‐impregnated cells
Authors: Albers F. Johannes , Meek Johannes 
Published: May 2005

AbstractThe present study deals with a light‐ and electron microscopic morphometric analysis of Golgi‐impregnated neurons in the superior colliculus of rats with the purpose to unravel inter‐ and intralaminar differences in their dendritic and synaptic organization. In particular, layer IV was studied and compared with its boundary layers III and V.The results show that collicular cells in layer IV basically form a homogeneous population with respect to the number of primary dendrites, the total length of impregnated dendrites, and the diameter, ellipticity, and orientation of dendritic fields and somata of Golgi‐impregnated neurons.Somata of reconstructed small cells in layer III and IV as well as V have all a similar density of about 40 synaptic contacts per 100 μm2 surface. However, the cell bodies of large multipolar cells in layer V have a slightly but significantly larger synaptic density (about 50 per 100 μm2). Dendrites of large and small collicular cells had no significantly different synaptic densities (43 and 48 per 100 μm2, respectively).In conclusion, the present results show only minor dendritic and synaptic differences between individual cells in the same layer, as well as in neighboring layers, which implies a low degree of cellular and synaptic intra‐ and interlaminar differentiation. It is discussed that this organization differs markedly from that in other visual centers, including the collicular homologue, the tectum of lower vertebrates, and the mammalian visual cortex, where pronounced inter‐ and intralaminar differentiations exist. Such an organization may provide a framework of laminar specificity by which distinct cell types may select a restricted set of input out of all information available. The present quantitative investigation suggests that a similar framework is not present in the superior colliculus.
Anatomical relationships between sensory afferent arborizations in the cricket cercal system
Authors: Jacobs Gwen A. , Nevin Rocky 
Published: May 2005

AbstractThe anatomical relationships between sensory afferents within a topographic map in the cricket cercal sensory system were studied using a computer‐based reconstruction system developed in our laboratory. Individual identified mechanosensory afferents were characterized physiologically, stained with cobalt, silver intensified, and reconstructed in three dimensions. All reconstructions were scaled to a common standard. The results indicate that there is very little variability in the position or extent of the terminal arborization of identified mechanosensory afferents. The topographic map was divided relatively equally into four regions representing each of the four classes of afferents studied. These regions were discrete but not completely segregated. Approximately 30% of the topographic map contained regions of overlap between two or more classes or afferents.
Verification of the disector method for counting neurons, with comments on the empirical method
Authors: Pover Carolyn M. , Coggeshall Richard E. 
Published: May 2005

AbstractThe empirical and disector methods are unbiased sampling methods for determining numbers of neurons. The present study verifies and thus calibrates these methods by determining true numbers of ganglion cells in serial reconstructions and then using each method to estimate the same populations. The empirical method gives accurate counts but is laborious (inefficient). Five separate disector analyses, distinguished by height (h), were done for each ganglion. The findings are: (1) that the estimates are consistently low when h is minimal (reference and look‐up sections are adjacent), but (2) the estimates are accurate when h is greater (one to four sections intervene between reference and look‐up sections). We ascribe the difficulties with the first disector to “lost” or “invisible” caps. We emphasize that we would not have known of the problem unless we verified our counts. If there is suspicion that difficulties with profile recognition might occur, we recommend that serial sections of an appropriately chosen sample of tissue be prepared and 500–1,000 neurons (or, more generally, particles) be reconstructed. Then the method of choice can be used on the issue of choice to make certain of the necessary accuracy before proceeding with the main study.
Layered collagen fabric of cerebral aneurysms quantitatively assessed by the universal stage and polarized light microscopy
Authors: Canham Peter B. , Finlay Helen M. , Dixon Jan G. , Ferguson Sarah E. 
Published: May 2005

AbstractWe evaluated the effectiveness of the Universal stage, an instrument for measuring three‐dimensional orientation of birefringent materials, for studying the collagen fabric in the wall of brain aneurysms. Vessels from autopsy were fixed at normal arterial distending pressure with 10% formalin, and prepared for polarized light microscopy, with paraffin embedding and staining with picrosirius red for birefringent enhancement. Quantitative data were obtained from tangential and oblique sections (7 μm thickness) of an intact 8 mm aneurysm, a 1.5 mm aneurysm, and a tangential section (3 μm thickness) of a cerebral artery. Sections of full‐size aneurysms seen through the microscope, adjusted either for plane or circularly polarized light, revealed distinctive layers of collagen across the aneurysmal wall, which at higher magnification were further subdivided. Three‐dimensional measurements, numbering 1,082, were made by use of the Universal stage attachment to the polarizing microscope. They were plotted by computer‐controlled graphics on Lambert projections and analyzed by circular statistics. When assessed layer by layer, the collagen spanned a full range of orientations relative to the tangential plane. The circular standard deviation, a measure of the spread of alignment about the mean, was as low as 10° for coherently organized collagen and as high as 40° for the least coherently organized collagen, values characteristic of either the organized tunica media, or the least organized tunica adventitia of cerebral arteries. Although there was a marked thinning of the wall of one aneurysm, there was no evidence of structural weakness based only on the directional organization assessed by our measurements.
Morphometry and magnetic resonance imaging of the human brain in normal controls and Down's syndrome
Authors: Weis Serge 
Published: May 2005

AbstractA new powerful stereological tool for exact quantification of brain structures on magnetic resonance imaging (MRI) scans was used. Applying Cavalieri's principle, unbiased estimation of volume can be obtained. The method was applied to estimate the volume of different brain structures from normal controls. Data were used for comparison with data obtained by analyzing the brains of persons with Down's syndrome. A normalization procedure based on volume of cranial cavity is introduced and its advantages discussed, as is the coefficient of error as an indicator for the precision of the measurement.
Correlated biochemical and radioautographic studies of protein turnover in developing rat incisor enamel following pulse‐chase labeling with L‐[35S]‐ and L‐[methyl‐3H]‐methionine
Authors: Smith C. E. , Dahan S. , Fazel A. , Lai W. , Nanci A. 
Published: May 2005

AbstractThe movement of proteins into and out of enamel was followed over time using a highly sensitive microprecipitation technique to quantify the amount of TCA‐insoluble radioactivity present within small pieces of freeze‐dried enamel and cells (enamel organ) dissected from the mandibular incisors of rats injected with L‐[35S]‐methionine. Conventional image processing techniques were also used to estimate the number of silver grains over enamel and cells in radioautographs of mandibular incisors from rats similarly injected with L‐[methyl3H]‐methionine. Data from both techniques indicated that the average half‐life for labeled proteins secreted into enamel was about 8.9 days. Typically, radioactive proteins accumulated in increasing amounts for 8 hours after which they were lost slowly up to 4 days and more rapidly thereafter when enamel formed during the secretory stage underwent maturation. The half‐life for radioactive proteins in cells was only about 20.7 hours. No significant accumulation of radioactivity could be detected in the TCA‐soluble or TCA‐insoluble fractions of cells as enamel development proceeded. Results from this study suggest that radioautographs provide an accurate estimate of changes occurring to proteins in enamel and cells except at early time intervals (less than 1 hour) when a high percentage of total radioactivity is present within the TCA‐soluble fraction of cells.
An electron microscopic study on the presence of proteoglycans in the mineralized matrix of rat and human compact lamellar bone
Authors: Sauren Yvonne M. H. F. , Mieremet René H. P. , Groot Cornelis G. , Scherft Johannes P. 
Published: May 2005

AbstractThe presence of proteoglycans (PGs) was studied in compact lamellar rat and human bone at the electron microscopic level. With the cationic dye cuprolinic blue (CBI), PGs could be demonstrated in the mineralized bone matrix. The amounts of PGs appeared to be equal in the different lamellae and osteons. More CBI‐positive material was found in the outermost lamella of the cortex, in the perilacunar matrix around the osteocyte lacunae, and around the canaliculi. Enzyme digestion with chondroitinase ABC demonstrated that the CBI‐positive rods consisted of PGs. These observations amplify biochemical studies in which PGs have been isolated from the mineralized bone matrix. The presence of CBl‐positive rods in the mineralized matrix suggest that PGs do not have to be removed completely to make the matrix calcifiable.
Symmetrically banded collagen fibrils: Observations on a new cross striation pattern in vivo
Authors: Mallinger Rudolf , Kulnig Werner , Böck Peter 
Published: May 2005

AbstractCollagen fibrils with a symmetric banding pattern, an as yet overlooked component of the extracellular matrix, were found in the reticular layer of the basement membrane of human sebaceous glands. In longitudinal sections this newly described banding pattern is D‐periodic (D = 67 nm) resembling the period length of native type collagen fibrils. In cross sections the symmetrically banded fibrils are irregularly outlined. The period length and the symmetric banding pattern led to the assumption that collagen molecules are staggered by the distance D, similar to native type collagen fibrils, but are arranged antiparallel. This hypothesis was tested by antiparallel superposing transparent photocopies of native type fibrils. In addition, schematic drawings of the cross striation pattern of native type fibrils were superposed in reverse directions by means of computerized image‐manipulation. A model of molecular alignment was evolved from these experiments, which is characterized by two features: (1) pairs of antiparallel collagen molecules are D‐staggered and (2) the two molecules of a pair are slightly shifted from precise register. The proposed model is the only one correlating with the data obtained from direct measurements on symmetrically cross striated fibrils. The fibrils described in the present study represent a supramolecular aggregate of collagen previously not observed in vivo.
Lysosomal integral membrane proteins exhibit region and cell type specific distribution in the epididymis of the adult rat
Authors: Suarez‐Quian Carlos A. , Jelesoff Nicole , Byers Stephen W. 
Published: May 2005

AbstractThe epididymis, a post‐testicular site required for maturation and storage of spermatozoa, is actively involved in exocytic and endocytic events, two phenomena likely to depend on the integrity of the lysosomal system. To study the lysosmal system of the epididymis, five monoclonal antibodies, previously characterized as recognizing five distinct lysosomal integral membrane proteins (LIMPs 1–5), were used as molecular probes of lysosome distribution in cells lining the epithelium. Immunocytochemical localization of LIMPs, using biotin‐streptavidin immunoperoxidase methodology, was performed on frozen sections of adult rat epididymides and in cell cultures prepared from either the caput or cauda epididymis. In frozen sections, a heterogeneous distribution of the different LIMPs along the length of the epididymis was observed. For example, the distribution of LIMP 1 (35–50 K) was detected in all cells of the caput and quite dramatically in clear cells of the distal caput, corpus, and cauda epididymis, but specifically not in the principal cells of the distal caput, corpus, and cauda. In contrast, LIMP 2 (64–71 K) was present in all cells of the epidiyms, except clear cells. LIMPs 4 and 5 (93 K and 93 K) were detected in all epididymal cells, including the clear cells. Finally, whereas the regional and cell type distribution of LIMP 3 (74 K) in the epididymis was identical to that of LIMPs 4 and 5, the nature of the vesicles immunostained was distinct. In cultured cells, the general immunostaining patterns observed in vivo were maintained during the duration of the primary cultures for all five LIMPs. Our results begin to address the molecular heterogeneity of the lysosomal system along the lenght of the epidiymis, and may suggest in part a basis for underlying structural and functional characteristics of the epididymis leading to the sequential maturation of sperm.
Pathways of lymph flow through intestinal lymph nodes in the horse
Authors: Nikles Stephen A. , Heath Trevor J. 
Published: May 2005

AbstractIn the horse, several thousand lymph nodes receive lymph from the intestine, part of which is very large and contains microorganisms that enable the animal to utilize refractory dietary constituents such as cellulose. The aim of this study was to describe the pathways by which lymph is delivered into, traverses, and is drained from these lymph nodes. These pathways were studied with either Microfil or methacrylate casting materials and with light and electron microscopy.The afferent lymphatic vessel delivering lymph into one of the nodes divides over the capsular surface and within trabeculae into terminal branches, and these are continuous with the subcapsular and trabecular sinuses through rounded holes up to 30 μm across.Lymph is conveyed from the subcapsular and trabecular sinuses through the cortex by four types of sinuses: trabecular sinuses, cortical tubular sinuses, tubulelike sinuses with a network of stellate cell processes, and sinuses between cortical cords. It is conveyed through the medulla by sinuses both within and between medullary cords.Lymph is drained from these sinuses by initial efferent lymphatics of three types: those between medullary cords, those within the subcapsular sinus overlying medullary or cortical cords, and those within trabeculae. All three types are continuous with surrounding sinuses through holes 5–30 μm across. These three alternative routes for lymph drainage may ensure adequate lymph flow during different intranodal conditions that may exist when the node is responding to microcrganisms or other foreign materials.
Basement membrane and fibronectin matrix are distinct entities in the developing mouse blastocyst
Authors: Thorsteinsdóttir Sólveig 
Published: May 2005

AbstractImmunocytochemical techniques were used to study the distribution of fibronectin, type IV collagen (collagen‐IV), and laminin in four different stages of mouse blastocyst development. Immunoreactivity for collagen‐IV and laminin is present in a granular pattern inside the inner cell mass (ICM) cells in stage 1 blastocysts, while these blastocysts are negative for fibronectin. Fibronectin immunoreactivity appears extracellularly under the trophectoderm (TE) in stage 2 blastocysts, in the form of homogeneously distributed dots, and/or fibrils located preferentially close to cell boundaries. It is followed by the appearance of both collagen‐IV and laminin immunoreactivity in patches on the basal side of the TE in stage 3 blastocysts. These patches are initially localized under the central region of TE cells, thus in a location clearly different from that of fibronectinpositive fibrils. As development proceeds the collagen‐IV‐ and laminin‐positive patches become larger, covering, by stage 4, an extensive portion of the inner lining of the blastocoel. Fibronectin‐positive material is still present in a fibrillar form in stage 3 blastocysts, but is generally reduced to thin strands by stage 4. These results indicate that fibronectin is independent of the mouse blastocyst basement membrane, but may play a transient role in cell adhesion during its deposition. In addition, the results suggest that the ICM plays a major role in the production of collagen‐IV and laminin, while the basal surface of TE cells is the primary site of basement membrane assembly.
Anatomical evidence for a countercurrent heat exchanger associated with dolphin testes
Authors: Rommel Sentiel A. , Pabst D. Ann , McLellan William A. , Mead James G. , Potter Charles W. 
Published: May 2005

AbstractCetaceans possess cryptic testes that lie within the abdominal cavity, that are surrounded by primary locomotor muscles, and that are presumably exposed to core or above core body temperatures. It has remained a question as to how cetaceans produce and store viable sperm at these high temperatures. We offer anatomical evidence for a two layer arterio‐venous countercurrent heat exchanger at the cetacean testis. Subcutaneous veins from the peripheral surfaces of the dorsal fin and flukes carry cool blood from the fins to the lumbo‐caudal venous plexus. The lumbo‐caudal venous plexus is juxtaposed to the spermatic arterial plexus, which supplies the testis. Venous plexus flow is from the ventro‐lateral margins of the visceral cavity towards the vena cava. Arterial plexus flow is from the aorta towards the ventro‐lateral margins of the visceral cavity and into the testis. The existence of a countercurrent heat exchanger suggests that cetaceans potentially compensate for detrimental effects of core temperatures on sperm viability and storage by regulating the temperature of blood flow to the testis.
Use of biplanar radiographs for estimating cross‐sectional geometric properties of mandibles
Authors: Biknevicius Audrone R. , Ruff Christopher B. 
Published: May 2005

AbstractSeveral radiographic techniques for estimating bone cross‐sectional geometric properties of mandibular corpora are compared. A hollow symmetrical model significantly improves estimates compared to solid or hollow symmetrical models that have been used in previous studies. Using this model, biplanar radiographs can give sufficiently accurate information of the amount and distribution of cortical bone in a section given relatively regular subperiosteal and endosteal perimeters.