bluuebunny/crossref_metadata_2025_split huggingface dataset:
A study of intercellular bridges during spermatogenesis in the rat
Authors: Weber James E. , Russell Lonnie D. 
Published: February 2005

AbstractA morphological evaluation of intercellular bridges was undertaken during rat spermatogenesis. The dimensions and relationships of the bridges were shown to vary during different phases of spermatogenesis. Cellular divisions of spermatogonia and spermatocytes resulted in the partitioning of pre‐existing bridges by complex structures termed bridge partitioning complexes, which are described in detail, as is the process whereby new bridges are formed. The structure of premeiotic bridges was generally consistent; however, during spermiogenesis, the structure of bridges and bridge contents were modified at specific phases of their development. The plasmas membrane density associated with the cytoplasmic aspect of early step 1 spermatids separated into multiple dense bands that encircled the peripheral aspect of late step 1 spermatid bridges. By step 2 of spermiogenesis, these dense bands became associated with several cisternae of endoplasmic reticulum, which later coalesced into a single saccule that completely encircled the bridge structure by step 4. At steps 10–12 nm in diameter appeared within the bridge channel. At step 17 of spermiogenesis, the filament‐bounded densities were no longer apparent, but an anastomosing network of endoplasmic reticulum, often in the configuration of a sphere, occupied the entire central region of the bridge. In step 19 spermatids, the smooth endoplasmic reticulum within the bridge channel and the multiple cisternae lining the bridge density were gradually lost its prominence. Some cytoplasmic lobes were connected by extremely narrow (∼ 22 nm) cytoplasmic channels. Similar appearing channels were seen on the surface zone of cytoplasmic lobes or residual bodies, this observation suggesting that channels were sites of severence of bridges. Just prior to the separation or disengagement of the spermatid from the cytoplasmic lobe, selected bridges appeared to open to form large masses. After spermiation, residual bodies were not found joined by bridges; but from the size of some of the residual bodies, it was suspected that they were formed by coalescence of more than one cytoplasmic lobe. Freeze‐fracture demonstrated few intramembranous particles on either the P or E face of the plasma membrane forming the bridge; this finding suggested bridge structures restricted free lateral movement of membrane constituents across the bridge. Collectively, the date demonstrated that bridges are not static structures but show size variations and considerable structure‐related diversity during spermatogenesis.
Actin localization in male germ cell intercellular bridges in the rat and ground squirrel and disruption of bridges by cytochalasin D
Authors: Russell Lonnie D. , Vogl A. Wayne , Weber James E. 
Published: February 2005

AbstractFilaments about 6–7 nm in diameter were seen associated with germ cell intercellular bridges in detergent‐permeabilized cells treated with tannic acid. Approximately 40–50 filaments were present subjacent to the bridge density. Filaments encircled the bridge channel in a manner similar to contractile ring actin filaments of dividing cells. NBD‐phallacidin and myosin S‐1 subfragments were employed to demonstrate that the filaments observed at intercellular bridges are actin. Intratesticular injection of a single dose of cytochalasin D, a specific inhibitor of actin filaments, caused certain intercellular bridges of spermatids to open within 3 hr after injection, leading to the production of symplasts. During bridge opening, remnants of bridge densities were gradually incorporated into the lateral aspect of the plasma membrane of the symplast. Thus actin, present in bridge structures, appeared to participate in maintaining certain intercellular bridges. A model of intercullar bridge structure is presented.
Morphometry and cytochemistry of leydig cells in experimental diabetes
Authors: Anderson J. E. , Thliveris J. A. 
Published: February 2005

AbstractLeydig cell ultrastructure and function in diabetic rats were studied by concurrent cytochemisty, morphometry, and testosterone assay. The streptozotocin (Stz) model was modified to include nondiabetic Stz‐injected rats, an insulin‐treated diabetic group, and semistarved animals in addition to controls and untreated diabetic rats. The separation of the effects of diabetes, Stz, semistarvation, and insulin treatments was achieved by application of orthogonal contrast statistics.After 3 months of treatments, testes were perfusion fixed, incubated Δ5,3β‐hydroxysteroid dehydrogenase (HSD) activity, and processed for electron microscopy.Diabetes increased Leydig cell smooth endoplasmic reticulum (SER), increased mitochondrial and lipid content, decreased HSD staining, and decreased serum testosterone levels. Insulin treatment reduced SER and increased testosterone concentrations. Semistarvation also increased SER and reduced testosterone levels but did not alter HSD staining. Stz had no significant effect on these variables. The results suggested that the hypoandrogen state was due to a primary Leydig cell compromise and not solely to malnutrition and that it was correctable by insulin treatment.
Secretion of proteins and glycoproteins by perifused rabbit corpus epididymal tubules: Effect of castration
Authors: Orgebin‐Crist Marie‐Claire , Hoffman Loren H. , Olson Gary E. , Skudlakek Marjorie D. 
Published: February 2005

AbstractProtein synthesis in epididymal tissue of intact and castrated rabbits was studied after incubation of epididymal minces with [35S]‐cysteine or [35]‐methionine and protein separation by two‐dimensional gel electrophoresis. Regional differences in the pattern of protein synthesized were observed. Castration did not change overall protein synthesis, but it reduced these regional differences. The presence of 5α‐DHT in the culture medium of the proximal corpus epididymidis perfused for 24 hr did not increase overall protein synthesis in tubules from intact or castrated rabbits and did not reinitiate synthesis of the proteins that had disappeared after castration.The kinetics of glycoprotein synthesis and secretion were studied by light and electron microscopy autoradiography at 0.5, 2, 6, and 24 hr after exposure to [3H]‐mannose, [3H]‐fucose, and [3H]‐glucosamine. Changes in the distribution of msinnose‐ and glucosamine‐labeled material indicated that the decline in grain density over the epithelium from 30 min to 24 hr coincided with an increasing reaction over the stereocilia border from 30 min to 2 hr and in thejumen from 2 to 24 hr. The distribution of fucose‐labeled material indicated that the grain reaction over the epithelium declined more rapidly than with the mannose label. When the glucosamine‐labeled sperm mass was released from the tubules, the labeled material was lost after the first washing, indicating that the glucosamine‐labeled glycoproteins did not bind firmly to corpus spermatozoa within 24 hr. After castration, both mannose‐ and fucose‐labeled materials migrated to the cell apex more rapidly than in the intact animal, but they were not released as readily into the lumen. The culture of epididymal tubules from castrated males with 5a‐DHT for 24 hr did not promote the release of either mannose‐ or fucose‐labeled material into the lumen. However, testosterone given in vivo for 2 weeks restored secretion of mannose‐labeled material into the lumen.
Computer ranking of the sequence of appearance of 73 features of the brain and related structures in staged human embryos during the sixth week of development
Authors: O'Rahilly Ronan , Müller Fabiola , Hutchins Grover M. , Moore G. William 
Published: February 2005

AbstractThe sequence of events in the development of the brain in human embryos, already published for stages 8–15, is here continued for stages 16 and 17. With the aid of a computerized bubble‐sort algorithm, 71 individual embryos were ranked in ascending order of the features present. Whereas these numbered 100 in the previous study, the increasing structural complexity gave 27 new features in the two stages now under investigation. The chief characteristics of stage 16 (approximately 37 postovulatory days) are protruding basal nuclei, the caudal olfactory elevation (olfactory tubercle), the tectobulbar tracts, and ascending fibers to the cerebellum. The main features of stage 17 (approximately 41 postovulatory days) are the cortical nucleus of the amygdaloid body, an intermediate layer in the tectum mesencephali, the posterior commissure, and the habenulo‐interpeduncular tract. In addition, a typical feature at stage 17 is the crescentic shape of the lens cavity.
Distribution of connective tissue proteins in chick muscle spindles as revealed by monoclonal antibodies: A unique distribution of brachionectin/tenascin
Authors: Maier Alfred , Mayne Richard 
Published: February 2005

AbstractThe distribution in chick muscle spindles of eight connective tissue proteins (collagen types I, IV, V, and VI, laminin, heparan sulfate, fibronectin, and brachionectin/tenascin) was examined by immunofluorescent histochemistry. Intrafusal fibers were surrounded by layers of collagen type VI and fibronectin, and by an external lamina containing collagen type IV, laminin, and heppran sulfate. Most of these layers displayed a different pattern of staining at the sensory region of the equator than at the polar region. The crescent‐like sheath that caps each intrafusal fiber and sensory terminal at the equator was strongly positive for collagen type I and weakly positive for collagen type V. The outer spindle capsule contained laminin, heparan sulfate, collagen types IV and VI, brachionectin/tenascin, fibronectin, and to a lesser degree also collagen types I and V. Brachionectin/tenascin had the narrowest distribution of any of the connective tissue macromolecules studied. It was found only in the outer capsule and in the coverings of blood vessels and nerves associated with the outer capsule.
Innervation of the superficial pineal of the rat using retrograde tracing methods
Authors: Stanley Laura C. , Horikawa Kyoi , Powell Ervin W. 
Published: February 2005

AbstractFast blue (FB), rhodamine microspheres (RH), horseradish peroxidase (HRP), and wheat germ agglutinin‐horseradish peroxidase conjugate (WGA‐IIRP) were used as retrograde tracers to study the innervation of the rat superficial pineal gland (SP). One of the tracers was injected into the gland of each animal. All four retrograde tracers injected into the gland always labeled neurons in the superior cervical ganglia (SCG). No retrograde labeling was ever seen in the suprachiasmatic nuclei, paraventricular hypothalamic nuclei, lateral hypothalamus, habenular nuclei, amygdalar nuclei, or superior salivatory nuclei. Retrograde labeling was seen in the anterior hypothalamic nuclei, anterior thalamic nuclei, lateral geniculate bodies, and midbrain tectal structures when a tracer spread from the injection site to the overlying cortex, tectum, or commissures. Control studies included injection of tracer into the subarachnoid space around the SP or into structures adjacent to the SP. Only the injection of FB or WGA‐HRP into the subarachnoid space labeled neurons in the SCG. This labeling was probably due to the spread of tracer to the choroid plexus. These results agree with recent work confirming the existence of a direct projection of the SCG into the interstitium around pinealocytes. The evidence does not substantiate an innervation originating in the habenular nuclei; the superior salivatory nuclei; or any other diencephalic, midbrain, pontine, or medullary structure.
Nonolfactory surface epithelium of the nasal cavity of the bonnet monkey: A morphologic and morphometric study of the transitional and respiratory epithelium
Authors: Harkema Jack R. , Plopper Charles G. , Hyde Dallas M. , Wilson Dennis W. , St. George Judith A. , Wong Viviana J. 
Published: February 2005

AbstractThe purpose of the present study was to characterize ultrastructurally the nonolfactory nasal epithelium of a nonhuman primate, the bonnet monkey. Nasal cavities from eight subadult bonnet monkeys were processed for light microscopy, and scanning and transmission electron microscopy. Nonolfactory epithelium covered the majority of the nasal cavity and consisted of squamous (SE), transitional (TE), and respiratory epithelium (RE). Stratified SE covered septal and lateral walls of the nasal vestibule, while ciliated pseudostratified RE covered most of the remaining nasal cavity. Stratified, nonciliated TE was present betwen SE and RE in the anterior nasal cavity. This epithelium was distinct from the other epithelial populations in abundance and types of cells present. TE was composed of lumenal nonciliated cuboidal cells, goblet cells, small mucous granule (SMG) cells, and basal cells, while RE contained ciliated cells, goblet cells, SMG cells, basal cells, and cells with intracytoplasmic lumina lined by cilia and microvilli. TE and RE contained similar numbers of total epithelial cells and basal cells per millimeter of basal lamina. TE was composed of more SMG cells but fewer goblet cells compared to RE. We conclude that nonolfactory nasal epithelium in the bonnet monkey is complex with distinct regional epithelial populations which must be recognized before pathologic changes within this tissue can be assessed adequately.
Distribution of somatostatinlike immunoreactivity in the brain of the little brown bat (Myotis lucifugus)
Authors: Cotter John R. , Laemle Lois K. 
Published: February 2005

AbstractThe distribution of somatostatinlike immunoreactive (SLI) perikarya, axons, and terminals was mapped in subcortical areas of the brain of the little brown bat, Myotis lucifugus, using light microscopic immunocytochemistry. A preponderance of immunoreactivity was localized in reticular, limbic, and hypothalamic areas including: (1) in the forebrain: the bed nucleus of the stria terminalis; lateral preoptic, dorsal, anterior, lateral and posterior hypothalamic areas; amygdaloid, periventricular, arcuate, supraoptic, suprachiasmatic, ventromedial, dorsomedial, paraventricular, lateral and medial mammillary, and lateral septal nuclei; the nucleus of the diagonal band of Broca and nucleus accilmbens septi; (2) in the midbrain: the periaqueductal gray, interpeduncular, dorsal and ventral tegmental, pretectal, and Edinger‐Westphal nuclei; and (3) in the hindbrain: the superior central and parabrachial nuclei, nucleus incertus, locus coeruJeus, and nucleus reticularis gigantocellularis. Other areas containing SLI included the striatum (caudate nucleus and putamen), zona incerta, infundibulum, supramammiilary and premammillary nuclei, medial and dorsal lateral geniculate nuclei, entopeduncular nucleus, lateral habenular nucleus, central medial thalamic nucleus, central tegmental field, linear and dorsal raphe nuclei, nucleus of Darkschewitsch, superior and inferior colliculi, nucleus ruber, substantia nigra, mesencephalic nucleus of V, inferior olivary nucleus, inferior central nucleus, nucleus prepositus, and deep cerebellar nuclei. While these results were similar in some respects to those previously reported in rodents, they also provided interesting contrasts.
Functional maturation of the capillary wall in the fetal and neonatal rat heart: Permeability characteristics of developing myocardial capillaries
Authors: Porter Glyn A. , Bankston Patrick W. 
Published: February 2005

AbstractThe development of the functional components of the myocardial capillary wall was characterized by time‐course studies of transendothelial transport of intravascularly injected probes of graded size from 16 days of gestation in the fetal rat to seven days postpartum. Despite the morphological changes occurring in the developing endothelial cells, the interaction of the probes was similar throughout the developmental period studied. The carbon particles were retained within the capillary lumina without any association with interendothelial junctions or with plasma‐lemmal vesicles. Carbon also was associated with coated vesicles. In contrast to carbon, ferritin was localized sequentially, over 60 sec of circulation, in plasmalemmal vesicles on the lumenal surface, in the cytoplasm, and on the ablumenal surface of the endothelial cells as well as in the interstitial space. Ferritin was located also in coated pits and vesicles and, after 90 sec of circulation, in multivesicular bodies. Within 30 sec of circulation, reaction product of myoglobin was located in plasmalemmal vesicles, coated vesicles, and transendothelial cell channels. Also within 30 sec, myoglobin partially filled the interendothelial space from the capillary lumina to the level of the tight junction. At all developmental ages studied, the interendothelial cell junctions appeared structurally tight and were impermeable to all of the probes. Once ferritin or myoglobin had reached the ablumenal space, the basal lamina did not appear to restrain the passage of the probes. Plasmalemmal vesicles are the capillary structures which transendothelially transport ferritin and myo‐globin in developing myocardial capillaries.
Atypical localization of myenteric neurons in the opossum lower esophageal sphincter
Authors: Sengupta A. , Paterson William G. , Goyal Raj K. 
Published: February 2005

AbstractThis study investigated sphincter‐body differences in neuronal density and morphometry between the esophageal sphincter and body with a view to determining whether previously reported differences are authentic. The anatomical limits of the opossum lower esophageal sphincter were correlated with its physiological behavior by manometric demarcation. Following this, peeled whole mounts and paraffin and cryosections were used to study the morphology and morphometry of the esophageal myenteric plexus. Thirty animals were used and seven quantitated. The plexus of the esophageal body was located as usual in a plane between the longitudinal and circular muscle, which coincided with the plane of cleavage when these muscle layers were peeled apart for studying the plexus in whole mounts. In contrast, the plexus was located in several planes in the lower esophageal sphincter, Which had no cleavage plane. Therefore, peeling the sphincter removes neurons and yields falsely low counts, making peel preparations of this region unsuitable for neuronal quantitation. In paraffin sections, the neuron density in the esophageal body 7 cm above the sphincter was 6,353±850/cm2but decreased significantly to 2,254±353/cm2 at the 1‐cm segment. In the lower esophageal 8,530±1,606/cm2. Flash‐frozen cryosections, which produced neuronal morphology similar to the in vivo condition, showed that there was no difference in neuronal size between esophageal body and sphincter. These studies show that atypical myenteric plexus localization causes spuriously low neuronal counts reported in the lower esophageal sphincter and that reported neuronal size differences are technique‐dependent.
Survival of myogenic cells in freely grafted rat rectus femoris and extensor digitorum longus muscles
Authors: Phillips Gregg D. , Lu Danyun , Mitashov Victor I. , Carlson Bruce M. 
Published: February 2005

AbstractThe objective of this study was to determine how long myogenic cells can survive in the central ischemic zone of early free muscle grafts in the rat. The study was conducted on free grafts of a large (rectus femoris) and a small (extensor digitorum lon‐gus) muscle. At times ranging from zero hr to five days post‐grafting, the central zones were isolated, minced, and implanted under the back skin of mice. After five days the minces were removed and examined histologically for the presence of rat myotubes, which should form only in minces that contain viable myogenic cells. The results show that myogenic cells survive two to four hr in the ischemic centers of the large rectus femoris grafts; after longer post‐grafting intervals, rat myotubes did not arise in central zone minces. In grafts of small muscles, myotubes consistently appeared in central zone minces. Since the formerly ischemic central areas of rectus muscle grafts are ultimately replaced by regenerating muscle fibers, we conclude that these regenerating muscle fibers are derived from precursor cells located outside of the ischemic zone.
Kidney of the great indian rhino Rhinoceros unicornis, linnaeus
Authors: Maluf N. S. R. 
Published: February 2005

AbstractThe kidney of R. unicornis has almost 80 closely apposed lobes, all appearing peripherally. Every lobe, almost enclosed by a collagenous septum, resembles a deformed truncated cone. The pelvis proper is a small pouch which divides into a cephalic and a caudal urothelial‐lined fibromuscular conduit. The terminal collecting ducts of every lobe open into a tubus maximus. This is lined by cuboidal cells and otherwise has no wall. There is no papilla. All lobes finally empty through the 18 primary infundibular orifices at the pelvic conduits. A primary fibromuscular infundibulum typically yields a secondary one supplying an adjacent lobe. Two or three lobes can use a common tubus maximus by “convergence” of their medullae.Tubus maximus, terminal collecting ducts and deep outer medulla are embraced by a fibromuscular calyx which is the peripheral extension of an infundibulum and is fused to the outer medulla. There is thus no vault between medulla and calyx. Large intralobar veins are fused to the outer wall of the calyx. The possible significance of this is discussed.The cortex is the only part of a lobe which has contact with infundibulum, pelvic conduits, or pelvis proper.The kidney has about 16 million glomeruli which form 5.8% of the adult's cortical mass. Many adult mammals, from mouse to rhinoceros, fit into the log10‐log10 slope relating number of glomeruli per kidney to body‐mass. Neonatal rhinos at term have mature glomeruli throughout the cortex. The small size of the glomeruli and the large number per field allow 16 million in an 118‐gm kidney.
Immunocytochemical study using a GABA antiserum for the demonstration of inhibitory neurons in the rat locus ceruleus
Authors: Ijima Koichi , Ohtomo Kazuo 
Published: February 2005

AbstractThe localization of GABA‐like immunoreactivity in the locus ceruleus of rats was studied by the peroxidase‐antiperoxidase (PAP) method using a purified antibody raised against GABA applied to paraffin sections, with counterstaining by cresylecht violet, and to floating sections for preembedding immunoelectron microscopy. A few medium‐sized and some small neurons showed GABA‐like immunoreactivity in both nuclei and perikarya. The preferential localization of these immunopositive neurons in the marginal parts of the locus ceruleus suggests that they are inhibitory local circuit neurons located between this center and the afferent fiber systems. Some of the immunoreactive neurons displayed homogeneous and heterogeneous ( paired cells) patterns. Occurrence of the GABA‐GABA interaction is indicated. Immunopositive bouton forms are located close to every positive and negative neuron. Electron microscopy confirms GABA‐like immunoreactivity in both medium‐sized and small neurons of the locus ceruleus and demonstrates that immunoreactive boutons are axosomatic and axosoma spine symmetric synapses on immunopositive and immunonegative cell bodies. These immunocytochemical results support the existence of inhibitory interneurons in the locus ceruleus.