bluuebunny/crossref_metadata_2025_split huggingface dataset:
Distribution of diazo‐positive (argentaffin) cells in the small intestine of rats of various ages
Authors: Josephson R. L. , Altmann G. G. 
Published: February 2005

AbstractIn unit lengths of longitudinally cut histological sections of the rat small intestine, the number of diazo‐positive argentaffin cells was determined along with the number of other epithelial cells. From these results, the frequency of argentaffin cells among the epithelial cells was calculated. The number, as well as the frequency, was maximal in the proximal duodenum and progressively decreased to a minimum in the mid‐intestine. Thereafter, it increased progressively caudally to reach a second maximum in the terminal ileum. The frequency in the terminal ileum was almost as high as in the proximal duodenum. When calculated for the duodenum of various age groups, it decreased from eight to two argentaffin cells per 1000 epithelial cells from newborn to adult ages respectively. It was calculated furthermore that the total number of diazo‐positive argentaffin cells in the rat small intestine should be around six million. Considering that the argentaffin cells are renewed about every four days (Ferreira and Leblond, ′71), about 1.5 million of them should be formed as well as exfoliated daily.The cells in the villi were stained more intensely than in the crypts, indicating that the argentaffin cells accumulate granules as they migrate from the crypts toward the villus tips, where indeed, intensely stained exfoliating argentaffin cells were occasionally observed. It is suggested that the exfoliation of argentaffin cells full of granules may be a mode of secretion for 5‐hydroxytryptamine into the intestinal lumen.
Fine structural observations on the development of the sperm head in the mouse
Authors: Dooher G. B. , Bennett D. 
Published: February 2005

AbstractThe stages of spermiogenesis in the mouse were investigated with the electron microscope with emphasis on morphogenesis of the sperm head. The nucleus undergoes chromosomal condensation in the concluding stages of spermiogenesis. Chromosomal condensation proceeds centrifugally and in a caudal direction, beginning in the anterior third of the nucleus. It is proposed that chromosomes establish attachments to the nuclear envelope prior to the onset of chromosomal condensation and that this arrangement of the chromosomes is an orderly one which facilitates the condensation process.
The effect of enzymes on extracellular connective tissue components in the developing chick aorta
Authors: Newman Timothy L. , Low Frank N. 
Published: February 2005

AbstractThe fine structure of developing connective tissue components of the chick embryo aorta of eight and nine days incubation ages was studied after treatment with one of seven enzymes (α‐amylase, α‐chymotrypsin, collagenase, elastase, β‐glucuronidase, hyaluronidase, and trypsin). Both tissue pieces and thin sections of aldehyde‐fixed aorta and great vessels were utilized. All preparations were mounted on stainless steel grids and stained with silver metalloporphyrin, uranyl acetate, and lead citrate.The homogeneous component of elastic fibers (elastin) responded only to elastase, indicating that it was well characterized early in its development. Eight‐day elastin was less susceptible to digestion than nine‐day elastin. Microfibrils were only slightly responsive to the actions of α‐amylase and trypsin, while α‐chymotrypsin completely eliminated them. Of the three connective tissue components, unit collagenous fibrils showed the greatest response. Complete or nearly complete digestions were effected by α‐amylase, α‐chymotrypsin, collagenase, and trypsin. Less extensive effects were produced by β‐glucuronidase and hyaluronidase.
Supraependymal cells in recesses of the monkey third ventricle
Authors: Coates Penelope W. 
Published: February 2005

AbstractScanning electron microscopy reveals unique supraependymal cells in preoptic and infundibular recesses of 3‐ to 21 ‐week‐old monkeys. Most supraependymal cells are located on nonciliated areas, and characteristically have round bodies from which multiple branched processes extend. Surface spherules occur on cell bodies and processes. Processes exhibit local enlargements, interweave with processes from other cells, and penetrate underlying ependyma.
Long‐term effects of ionizing radiation on the rat spinal cord: Intramedullary connective tissue formation
Authors: Gilmore Shirley Ann 
Published: February 2005

AbstractThe purpose of this study was to evaluate by light microscopy the effects of ionizing radiation on spinal cords of rats irradiated when three days of age and killed at intervals up to 28 months after irradiation. The amounts of x‐rays administered (2,000 R; 1,000 R; 500 R) were those which had been demonstrated by short‐term studies in this laboratory to cause either no histopathologic changes or only transient, reparable alterations. The most significant and previously unreported finding was the development, usually restricted to the gray matter, of elongated, spindle‐shaped cells that produce prodigious amounts of fibers clearly demonstrated by the Wilder's reticular stain. In cases where extensive cellular development had occurred, these cells were oriented around the perikarya of the large ventral motor neurons and formed a well‐developed capsule of reticular fibers. This phenomenon occurred more frequently in rats receiving the greater amounts of radiation and killed 12 months or more after exposure. The other observation of interest was the development of lesser amounts of connective tissue‐producing cells in the dorsal gray matter, where these cells were seen initially in the substantia gelatinosa. The significance of these changes is discussed in relation to previously reported long‐term effects of ionizing radiation on the central nervous system.
Innervation of the rat lung. Acetylcholinesterase‐containing nerves of the bronchial tree
Authors: El‐Bermani Al‐Walid I. 
Published: February 2005

AbstractThe innervation to the bronchial tree of the rqt was studied using silver impregnation and methylene blue staining in conjunction with histochemical demonstration of acetylcholinesterase and one‐micron sections of osmium‐bed, plastic‐embedded material. Innervation to the bronchial structures enters the lung along two pathways: (1) in bundles of nerves along the bronchi (peribronchial bundles), and (2) as nerve bundles associated with bronchial arteries (periarterial bundles) to innervate bronchial arteries and respiratory passageways. Fibers within the peribronchial bundles and associated nerve cells contain acetylcholinesterase. Varicose nerve plexuses associated with bronchial muscle (intermuscular nerves) are acetylcholinesterase‐positive, as are the submucosal nerves. Submucosal nerves are of two types. One type originates directly from the peribronchial bundles after passing through the muscularis without innervating it. These nerves extend circumferentially and longitudinally with respect to the bronchiole. The second submucosal nerve type originates from the intermuscular nerve plexus. These nerves have a radial orientation within the bronchial submucosa and reach the mucosa. It is concluded that the intermuscular nerves are postganglionic parasympathetics. The two types of submucosal nerves are thought to perform different functions.
Postnatal development of the mouse dentate gyrus in organotypic cultures of the hippocampal formation
Authors: LaVail Jennifer H. , Wolf Merrill K. 
Published: February 2005

AbstractThe hippocampal formation of newborn mice was explanted and maintained in Maximow culture assemblies for up to 35 days. At the time of explantation, only the suprapyramidal limb of the dentate gyrus was cytoarchitectonically distinct, and electron microscopy of newborn hippocampus revealed no definitive synapses. Histogenesis, as indicated by the development of the infrapyramidal limb of the dentate gyrus, and synaptogenesis, as indicated by the in vitro formation of mossy fiber synapses on the dendrites of hippocampal pyramidal neurons were studied by light and electron microscopy. At 12 days and thereafter in culture, mossy fiber terminals were found in synapsis with dendritic spines probably belonging to pyramidal cells of the hippocampal zone CA4. Near dentate granule cell somata a few axosomatic and many axospinous and axodendritic synapses were found. The data indicate that granule cells of the developing dentate gyrus are capable of differentiation in vitro into a structure essentially equivalent to that developed in vivo. The granule cells may become arranged into a recognizable granule cell layer, and develop dendritic processes which receive synapses virtually identical to those found in the intact organ. The differentiation of these features proceeds in the absence of the extrinsic afferents from the septum or from the contralateral hippocampal formation.
Structure and cytochemistry of the acinar cell in the rat maxillary gland
Authors: Vidić Branislav 
Published: February 2005

AbstractThe ultrastructural and cytochemical properties of the maxillary gland were investigated in 24 adult Sprague‐Dawley rats of both sexes. The relationship between the interstitial cell and/or excitatory cholinergic terminals with the secretory cell was discussed. The secretory material containing primarily neutral lipids, proteins, carbohydrates and mucosubstances appeared electron‐opaque following staining with uranyl acetate and lead citrate. Ruthenium red precipitated strongly on zymogenic granules which showed an increasing affinity for phosphotungstic acid, paralleling a rise in pH towards 7.7. The process of fusion of the plasma membrane with the membrane of secretory granules was observed, although some membrane‐bound granules were identified in the acinar and ductal lumina. Intracellular membranous structures were best revealed with phosphotungstic acid at pH 1.0–1.5, whereas ruthenium red reacted primarily with lipid inclusions and tonofilaments. Acid phosphatase activity was predominantly limited to secondary lysosomes and, to a lesser degree, to primary lysosomes and Golgi saccules. The morphological and chemical properties of secondary lysosomes in the secretory cell suggested a pronounced hydrolytic activity related to lipid inclusions and endocytotic vesicles.
The fine morphology of mouse primordial germ cells in extragonadal locations
Authors: Zamboni L. , Merchant H. 
Published: February 2005

AbstractThe localization and morphologic characteristics of mouse primordial germ cells at stages of embryonal development preceding formation of the undifferentiated gonads have been studied by means of high resolution light microscopy and electron microscopy. At day 9 of intrauterine life, the germ cells are found in the wall of the hind‐gut, at days 10 and 11 in the dorsal mesentery, and at day 12 they are mostly in the genital ridges or adjacent areas. Our observations confirm the hypothesis that germ cells attain their definitive location by ameboid movements. On the basis of morphologic characteristics displayed during migration, germ cells appear to be highly undifferentiated elements; for their energy requirements, they may depend on close association with somatic cells and on availability of exogenous substances of metabolic importance. Upon arrival at the genital ridges, the cells lose their ameboid features and assume a structural organization which is much simpler than that of precedinng stages. This indicates that migration is followed by a period of relative quiescence; mitosis is now the only evident activity. Interphase cells may occasionally be connected by intercellular bridges; it would seem that the first mitotic divisions with incomplete cytokinesis, a feature known to characterize oogonia and spermatogonia in sexually differentiated gonads, occur shortly after arrival of the germ cells in the genital ridges.
Studies on the progestational endometrium of the rabbit. I. Light microscopy, day 0 to day 13 of gonadotrophin‐induced pseudopregnancy
Authors: Davies J. , Hoffman L. H. 
Published: February 2005

AbstractA study of the progestational evolution of the endometrium of the rabbit in pseudopregnancy suggests a division into the following phases: (1) priming phase (0–24 hours), in which no significant changes were observed except for leucocytic invasion of the epithelium, (2) proliferative phase (1–4 days), in which mitosis is active and the epithelium becomes pseudostratified and the glands proliferate, (3) phase of epithelial relayering and folding (4–6 days), in which the epithelium is single‐layered and there is evidence of secretory activity, (4) phase of cell fusion (6–8 days), in which the columnar cells fuse into multinucleated masses, and (5) maximally progestational phase (8–13 days), in which almost all the epithelial cells are multinucleated except for occasional ciliated cells, and, in some animals with evidence of the effects of high systemic levels of estrogen, extensive ciliation, especially antimesometrially. A final phase (6), not studied in detail, is a declining phase marked by degeneration and sloughing of the multinucleated epithelium and replacement with predominantly ciliated cells. Reconstruction of the minor mucosal folds, as distinct from the six or so major folds present in the non‐pregnant animal, shows that these are true elevations of the mucosa above the level of the mouths of the glands. The current concept of progestational changes in the endometrium of the rabbit as predominantly due to glandular proliferation is incorrect; this has important implications for analysis of the implantation process.
The effect of injected cycloheximide on early amphibian development
Authors: Manner Harold W. , Lau Peggy O. 
Published: February 2005

AbstractCycloheximide is a known inhibitor of cytoribosomal translation. Previously published results indicated that embryos cultured in cyclo‐heximide developed only to the midblastula stage. The current study involved injecting one μg of cycloheximide into each developing embryo of Rana pipiens. The three stages selected for the injection were the two‐cell, late four‐cell, and morula. The embryos stopped developing at the four‐cell, sixteen‐cell and midblastula stages, respectively. Control embryos injected at the same stages with Holtfreter's solution developed normally. The results would indicate that de novo protein synthesis is necessary, not just at the midblastula stage, but throughout the entire cleavage period. The results are discussed in light of previous investigations.
The ependymal surface of the lateral ventricle of the dog as revealed by scanning electron microscopy
Authors: Allen Delmas J. , Low Frank N. 
Published: February 2005

AbstractYoung dogs were perfused with buffered aldehydes at fluid pressures approaching normal physiological values. Surface tissue from the temporal horns of the lateral ventricles were prepared for scanning electron microscopy, using postosmication, critical point drying and gold‐palladium coating.The ependymal surfaces are mostly ciliated but nonciliated areas occur along the medial walls. The latter areas are characterized by depressions, pores, fenestrations and a unique population of supraependymal cells. These polymorphic cells probably represent both conductive (neuronal) and supportive (neuroglial) elements. Adjacent to cilia‐free areas, transitional zones are observed. Here, a net‐like surface pattern consisting of smooth hexagonal cells is outlined by microvilli of varying lengths and isolated tufts of cilia are present.
Fine structure of the venom gland epithelium of the south american rattlesnake and radioautographic studies of protein formation by the secretory cells
Authors: Warshawsky H. , Haddad A. , P. Gonçalves R. , Valeri V. , L. De Lucca F. 
Published: February 2005

AbstractThe South American rattlesnake venom gland is made up of secretory tubules lined by a simple columnar epithelium containing horizontal cells, mitochondria‐rich cells, and the principal cell type, the columnar secretory cells. This cell has a round basal nucleus and abundant rough endoplasmic reticulum, the cisternae of which are variably distended with flocculent material containing many dense intracisternal granules. The supranuclear Golgi apparatus is spherical, with stacks of flattened saccules at the periphery and large vacuoles containing masses of dense material, and other dense granules in the center. Similar but smaller granules are present at the apex where they fuse with the microvillus‐covered apical membrane and release their content into the lumen. Protein synthesis was studied in snakes injected with 3H‐tyrosine and sacrificed at several times after injection. Radioautographs showed reactions at one half and one hour over the ribosomes and membranes of the rough endoplasmic reticulum. At two hours the immature face of the Golgi apparatus was labeled. At four hours Golgi saccules and vacuoles with dense masses (secretory granules) were labeled, and at eight hours the dense masses within the secretory granules were heavily labeled both in the Golgi region and in the apex near the lumen. Labeled material was found in the lumen at two days. Intracisternal granules were first labeled at eight hours, and by two days reactions remained only over the flocculent content and intracisternal granules of the rough endoplasmic reticulum. Thus, venom protein was synthesized on the rough endoplasmic reticulum, migrated through the Golgi apparatus and accumulated in the dense masses of the secretory granules, which moved to the apex and were extruded. The labeling of intracisternal granules at eight hours and two days after injection indicated a storage nature for these granules.
Mucopolysaccharide in the glomerular basement membrane of a hibernator (1)
Authors: L. Zimny Marilyn 
Published: February 2005

AbstractThe glomerular basement membrane in the kidney of a hibernating 13‐lined ground squirrel, when compared with that of a non‐hibernating animal, stains positively with ruthenium red indicating the presence of acid mucopolysaccharide. This increased quantity of anionic material accompanying hibernation may be responsible for maintaining water and electrolyte balance by acting as a resin for the exchange of cations between the capillary and urinary spaces, attracting water and concentrating protein.
Ciliary activity in the human and Macaca nemestrina oviduct
Authors: Gaddum‐Rosse P. , Blandau R. J. , Thiersch J. B. 
Published: February 2005

AbstractThe direction of ciliary beat has been examined in vitro in human and pig‐tailed macaque (M. nemestrina) oviducts. Ducts removed under anesthesia were slit open longitudinally while submerged in Hanks solution at 37° C, and particulate matter was applied to the mucosal surface. Contrary to previous observations in pig and rabbit oviducts, transport of particles was consistently in a downward direction, toward the proximal (uterine) end, in the two species examined in this study.
The atrioventricular valves of the guinea‐pig. II. An ultrastructural study
Authors: Hibbs Richard G. , Ellison Jeffrey P. 
Published: February 2005

AbstractEach atrioventricular valve of the guinea‐pig consists of a core of connective tissue and muscle covered by endothelial cells. The muscle forms an annulus at the attached margin of the valve adjacent to the fibrous annulus. Some fibers from the lower part of the muscular annulus turn sharply toward the free margin of the valve and form a complex meshwork. These fibers resemble atrial muscle, but are noteworthy in that each contains myofibrils that are oriented in different directions. Some muscle fibers have features similar to those of conducting fibers, i.e., glycogen rich cytoplasm containing few myofibrils. Unmyelinated nerve fibers are numerous in both the mitral and tricuspid valves, but myelinated fibers were found only in the mitral valve. Typical adrenergic terminals were found adjacent to some cholinergic endings. Mitochondria‐filled terminals (sensory?) and a third type of motor terminal were present also. Bundles of collagenous fibers extend from the chordae tendineae into the valve cusps where they fan out into small bundles. The other formed elements of the stroma are microfibrils and a flocculent material. There are a few elastic fibers beneath the endothelium. Interstitial cells, many of which possess solitary flagella are scattered throughout the matrix.
Histochemical changes in developing mouse liver after administration of phenobarbital
Authors: Richards Thomas C. 
Published: February 2005

AbstractThe effects of phenobarbital on development of some microsomal enzymes and neutral lipid were studied in mouse liver during a period of rapid cell differentiation. Specific alterations attributable to phenobarbital were identified in developing liver and used as markers for the onset of certain aspects of cell maturation. This investigation was designed to determine (1) the earliest developmental age at which fetal liver can react to phenobarbital and (2) the nature of the alterations in developing and adult liver.Intraperitoneal injections of phenobarbital were given for three days to 14, 17 and 19 day pregnant mice. Histochemical techniques were used to localize neutral lipid and the activities of NADPH diaphorase, glucose‐6‐phosphatase, and glucose‐6‐phosphate dehydrogenase. Total cell lipid was measured in livers from 17‐ and 19‐day pregnant mice and livers from their fetuses.The density of reaction product for NADPH diaphorase and glucose‐6‐phosphate dehydrogenase increased while glucose‐6‐phosphatase decreased in adult liver. Similar changes were seen in livers from day‐19 fetal animals but not in fetuses of younger ages. Neutral lipid droplets increased in size and number after phenobarbital in fetal mice of day 19 of gestation but not in mice of day 17 of gestation.It was concluded that liver from day‐19 fetal mice had gained the competence, lacking in earlier ages, to respond to phenobarbital by increased production of some enzymes and neutral lipid.
The corticotroph of the rat adenohypophysis: A comparative study
Authors: Bowie E. Phyllis , Williams Glenn , Shiino Masataka , Rennels Edward G. 
Published: February 2005

AbstractThe immunological and cytological specificity of antiserum to adrenocorticotrophic hormone was established and the corticotroph defined at the light microscopic level by immunocytochemistry. Our observations substantiated recent reports by several investigators. By comparing thin methacrylate sections with adjacent 1 μ‐methacrylate sections immunochemically stained with anti‐ACTH, the ACTH cell was identified at the ultrastructural level and its morphology studied. Using the criteria established at light and electron microscopic levels, the corticotroph was readily found in tissue which had been fixed in paraformaldehyde‐osmium mixture and embedded in epoxy resin. Ultrastructural changes in this cell in response to experimentally designed alterations in the pituitary ACTH levels confirmed this identification. The ACTH cell was likewise identified in glutaraldehyde‐fixed material. Thyrotrophs were tentatively defined. Several ultrastructural studies responsible for conflicting reports in the literature were investigated. It was concluded that the corticotroph is a unique cell type and that granule size and morphology remain important criteria for adenohypophyseal cell identification regardless of the fixation used. The need for a definitive immunocytochemical study of thyrotrophs at the ultrastructural level was recognized.
Enzymatic digestion of presynaptic structures in electroreceptors of elasmobranchs
Authors: Szamier R. Bruce 
Published: February 2005

AbstractSites of synaptic transmission between receptor cells and afferent nerves in electroreceptors of elasmobranchs are distinguished by a dense presynaptic ribbon surrounded by synaptic vesicles. Digestion by pronase or protease of thin sections of Epon embedded tissue selectively removes the presynaptic ribbon without affecting other synaptic structures. Presynaptic ribbons are composed in part of protein which differs significantly from other components of the synaptic complex.