bluuebunny/crossref_metadata_2025 huggingface dataset:
Changes in binucleation and cellular dimensions of rat left atrial myocytes after induced left ventricular infarction
Authors: Oberpriller John O. , Oberpriller Jean C. , Aafedt Bradley C.
Published: February 2005

The left atrium of young rats has previously been demonstrated to respond with DNA synthesis and binucleation 11 days after left ventricular infarction. This investigation was designed to examine the hypertrophic response of the left atrial myocyte of the rat at 20 and 60 days after ventricular infarction. Male Sprague‐Dawley rats were subjected to left coronary artery ligation (CAL) or sham operation. Following enzymatic separation, left atrial myocytes were examined at 20 and 60 days postoperation for number of nuclei and cellular dimensions (cell length, width and area, and nuclear area). Results demonstrated that the level of binucleation at 20 days (77.3%) and 60 days (71.3%) was nearly twice that observed in sham‐operated animals, which were 33.1% binucleated at 20 days and 43.5% binucleated at 60 days. In both mononu‐cleated and binucleated myocytes, the mean lengths, widths, and cell areas from CAL hearts were significantly greater than those of corresponding sham‐operated animals. In all cases, these values were larger in binucleated myocytes than in mononucleated cells. The mean area of CAL cells was approximately twice that of sham‐operated myocytes. With regard to mean lengths and widths, although both were greater in the CAL animals, there was a decrease in length and increase in width between 20 and 60 days in the CAL group. Mean nuclear areas were significantly greater in CAL myocytes than in those from the sham‐operated group. These increases in nuclear number and cellular dimensions of the atrial myocyte are prominent features of the response to the stress imposed by left ventricular infarction.
Luteal morphology, atresia, and plasma progesterone concentrations during the reproductive cycle of two oviparous lizards, Crotaphytus collaris and Eumeces obsoletus
Authors: Fox Sandra L. , Guillette Louis J.
Published: February 2005

From ovulation to oviposition, the corpora lutea of the oviparous lizards Crotaphytus collaris and Eumeces obsoletus exhibit three stages of luteal development: (1) luteogenesis, (2) luteal maturity, and (3) luteal regression. Each stage exhibits distinct characteristics, involving changes in: (1) luteal volume, (2) nuclear diameter of cells within the luteal cell mass, and (3) thecal development. Plasma progesterone concentration is greatest during luteogenesis and is positively correlated with ovarian atresia, although atresia occurred throughout the period of gravidity. These data suggest that in these two species, the corpora lutea secrete high amounts of progesterone immediately following ovulation and exhibit morphologically distinct stages of growth and regression.
In vitro behavior of thymic nurse cell‐like complexes from mechanically and enzymatically dissociated frog tadpole thymuses
Authors: Holtfreter Hiroko B. , Cohen Nicholas
Published: February 2005

Cellular complexes, analogous by virtue of their external appearance, size, and number of seemingly internalized thymocytes to thymic nurse cells (TNCs) of endothermic vertebrates, were seen in short‐term cultures (6–8 days) of mechanically and enzymatically dissociated thymuses of leopard frog tadpoles. Most TNC‐like complexes from mechanically disrupted thymuses were covered with many thymocytes that morphologically resembled the “internalized” thymocytes. With time in culture, most complexes remained spherical and lost their externally adherent and “internalized” thymocytes. Some complexes, however, adhered to the glass substratum by means of macrophage‐like cells. After one typically appearing TNC from a mechanically dissociated thymus had released its “internalized” thymocytes and spread completely over the glass substratum, it could be seen to consist actually of 9–10 stromal cells with the appearance of epithelial cells, macrophages, and dendritic cells. TNC‐like structures from enzymatically dissociated thymuses had few, if any, attached thymocytes. Although these structures closely resembled murine TNCs initially, they displayed abnormal transformations within a few days of culture. Our observations led us to question the assumption that all TNCs from mechanically as well as enzymatically isolated TNCs from vertebrate thymuses are single cells. Rather, some if not all of the so‐called TNC may actually be entities composed of several stromal cell types that enclose thymocytes. We suggest that this configuration seen in vitro may reflect the architecture of the compartmentalized reticular stromal cell meshwork that characterizes the intact thymus.
Histological, histochemical, and fine structural observations on the spleen of seals
Authors: Schumacher Udo , Welsch Ulrich
Published: February 2005

Spleens of three species of Antarctic seals with different diving habits (Weddell seal, crabeater seal, and fur seal) have been studied with histological, histochemical, and electron microscopic methods. The spleens can be classified as nonsinusoidal, with capsule and trabeculae rich in innervated smooth muscle cells. The trabecular system is particularly well developed in the deep‐ and long‐diving Weddell seal. As in other mammals the pulp can be divided into white and red pulp. In the white pulp, periarteriolar lymphatic sheaths and secondary lymphatic nodules occur; both are surrounded by a marginal zone rich in macro‐phages and eosinophils. The nodules can be observed frequently, which is in accordance with abundance of plasma cells in the red pulp. Well‐developed white pulp and numerous plasma cells and eosinophils obviously reflect a high load of nematodes, which have mainly been found in lung and stomach. Additionally, in the red pulp morphological evidence for the following functions has been found: destruction of erythrocytes, erythropoiesis, and thrombopoiesis. In respect to blood flow through the red pulp, we interpret our observations in the following way: terminal branches of arterioles open into the space between the fibroblastic reticulum cells; blood draining from here is collected into pulp veins, which are mainly found near the trabeculae. Thus, the seals have an open vascular compartment in their spleens, as also occurs in the cat. The red pulp is innervated by numerous nerve fibers that seem to include both cholinergic and adrenergic ones. The target cells of these fibers seem to be the fibroblastic reticulum cells, whose state of contraction may influence the direction of blood flow through the red pulp.
A study of intercellular bridges during spermatogenesis in the rat
Authors: Weber James E. , Russell Lonnie D.
Published: February 2005

A 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

Filaments 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

Leydig 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

Protein 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

The 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

The 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

Fast 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

The 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

The 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

The 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

This 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

The 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

The 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

The 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.
Development of the chorqid plexus anlage and supraependymal structures in the fourth ventricular roof plate of human embryos: Scanning electron microscopic observations
Authors: Otani Hiroki , Tanaka Osamu
Published: February 2005

The developing anlage of the choroid plexus and supraependymal structures in the fourth ventricular roof plates of nine normal human embryos ranging from Carnegie stages 14 to 19 were investigated with scanning electron microscopy. In the human embryos at stage 18, the first semimacroscopic choroidal anlage developed in the form of bilateral evaginations that ran dorsomedially and caudally from the bilateral corners of the rhombencephalon. The anlage became evident with even smaller and parallel ridges in the embryo at stage 19. Embryos at earlier stages exhibited surface membrane modifications such as convexity, microvilli, cilia, and spherical protrusions at the middle one‐third of the rhombencephalon, which corresponded to the future choroidal anlage region.

Two morphologically different groups of supraependymal cells (SE cells) were elucidated throughout the stages examined. Type 1 SE cells has spindle or teardrop‐like bodies, frequently with one or more long cy‐toplasmic processes. Type 2 SE cells were globular, with numerous fine pseudopodial processes. Type 1 SE cells were distributed mainly at the future choroidal anlage regions or on the anlage itself and were less frequently located at the rostral end of the roof. We found no general pattern in the distribution of type 2 SE cells. Supraependymal fibers (SE fibers) wete seen as fine processes that were distributed similarly to type 1 SE cells and extended transversely for a long distance.
Three‐dimensional canine renovascular structure and circulation visualized in situ with the dynamic spatial reconstructor
Authors: Bentley Michael D. , Hoffman Eric A. , Fiksen‐Olsen Mary J. , Knox Franklyn G. , Ritman Erik L. , Romero J. Carlos
Published: February 2005

The dynamic spatial reconstructor–a unique, high speed, volume‐scanning, X‐ray computed tomographic imaging system–was utilized to examine canine renovascular anatomy and renal circulation in situ. In each of the four kidneys examined in this study initial scans were done during bolus injections of angiographic contrast material into the renal artery. A subsequent scan was then performed following an injection of methyl‐methacrylate‐based casting compound that had been contrast enhanced with ethiodol. After the scans, each kidney was removed, and its parenchyma was digested in potassium hydroxide to expose the vascular cast. Comparison of casts with their reconstructed images and with images obtained during injection of contrast material showed that interlobar arteries and occasionally arcuate arteries could be clearly detected. Although discrete vessels less than 1 mm in diameter could not be resolved, dynamic changes in parenchymal distribution of density during passage of contrast material allowed interpretation of flow through the multiple capillary beds of the kidney. Such analysis indicated that maximal density was in the outer‐middle zone of the cortex throughout the duration of the scan. Analysis of artery‐to‐vein transit time showed arrival of contrast material in the renal vein as soon as 3 sec, and continuation for longer than 8 sec, after the renal artery bolus. In conclusion, renal circulation in the dog can be discretely visualized with the dynamic spatial reconstructor up to the level of the arcuate arteries; however, capillary flow as a whole can be followed through the cortex, and the results suggest the presence of both rapid and slow components of peritubular circulation.
Transitional cells at the junction of seminiferous tubules with the rete testis of the rat: Their fine structure, endocytic activity, and basement membrane
Authors: Hermo Louis , Dworkin Joel
Published: February 2005

Transitional cells line the intermediate region of rat seminiferous tubules situated between the rete testis and the seminiferous epithelium proper. These tall elongated cells orient themselves in a downstream direction and converge on one another distally in the lumen of the rete testis where they form a distinct papillalike structure through which a narrow patent lumen is apparent. In addition to widely dispersed Golgi apparatus and mitochondria, these cells contain an abundance of microtubules, cisternae of endoplasmic reticulum, and a distinct lobulated nucleus showing clumps of chromatin and a prominent nucleolus.

The endocytic activity of these cells was examined by employing adsorptive (cationic ferritin, concanavalin A ferritin) and fluid‐phase tracers (native ferritin, horseradish peroxidase‐colloidal gold complex, and concanavalin A ferritin in presence of a methyl‐D‐mannoside). Such tracers were injected separately into the lumen of the rete testis, and the animals were killed at 2, 5, 15, and 30 min and 1, 2, and 6 hr after injection. At 2 min, both adsorptive and fluid‐phase tracers were found within coated and uncoated pits of the apical plasma membrane of these cells as well as in large, subsurface, uncoated spherical, C‐shaped, and tubular membranous elements. At 5 min the tracers were seen in endosomes of different sizes; while at 15 min and 30 min, pale and dense multivesicular bodies of small and large sizes, respectively, were labeled. At 1‐hr and longer time intervals secondary lysosomes became labeled. While both fluid‐phase and adsorptive tracers followed the same pathway and fate, binding to the apical and lateral plasma membranes of the transitional cells and to the membrane delimiting coated and uncoated pits was observed only with the adsorptive tracers. These results demonstrate that the transitional cells are actively involved in both fluid‐phase and adsorptive endocytosis, which may play an important role in modifying the composition of the luminal fluid.

The transitional cells of the distal zone of the intermediate region rest on an elaborate basement membrane (BM) complex which includes a thin BM immediately underlying these cells, a thick distal layer of BM, and strands of BM spanning the distance between the two in the form of a loose anastomotic network. Use of antisera against heparan sulfate proteoglycan, laminin, and type IV collagen revealed the presence of all three components within all areas of the BM complex. In the meshes of the anastomotic BM network, extracellular vesicles were observed. Vesicles of similar size and appearance were also noted in the basal region of the transitional cells as well as in their basal‐foot‐like processes which extended deep into the meshes of the anastomotic network. While such extracellular vesicles may be derived from the transitional cells, their functional significance is as yet unclear.
Fine structure of the ventral and dorsal lobes of the prostate in the young adult syrian hamster, Mesocricetus auratus
Authors: Toma Jean G. , Buzzell Gerald R.
Published: February 2005

The normal ventral and dorsal prostatic lobes of the young adult Syrian hamster were examined at the light and electron microscopic levels. Each lobe is composed of branched tubular secretory units separated from each other by loose interacinar connective tissue and draining into the urethra. The lumen of each acinus is lined by a simple epithelium composed of columnar secretory cells with occasional small basal cells. The epithelial layer, with the thin underlying lamina propria, forms a mucosa that is often highly folded. The whole acinus is bounded by a thick muscular stroma.

In each of the ventral lobes, there are three main ducts, each one formed of tubular branched tributary secretory units. The walls of the secretory acini are moderately folded. Microvilli dominate the lumenal surface of the secretory epithelial cells. The Golgi complex is very extensive and shows dilated cisternae and secretory vesicles and vacuoles of various sizes. Membrane‐bounded secretory granules populate the Golgi and apical areas and are released into the acinar lumen by exocytosis. The rough endoplasmic reticulum is dispersed throughout the cytoplasm, except in the region of the Golgi apparatus.

In each of the dorsal lobes, there are several main tubular ducts that open into the urethra. Both proximal (ductal) and distal portions of the glandular tree are secretory in nature. Microvilli and cytoplasmic bulges and blebs dominate the lumenal surface of the secretory cells. The cells are also characterized by highly dilated cisternae of rough endoplasmic reticulum. The secretory cells show heterogeneity in the degree of dilation and distribution of rough endoplasmic reticulum, and this heterogeneity may reflect location in the glandular tree. Large dilated cisternae with irregular outlines are common in the basal portion of some cells, mainly those of the distended proximal (ductal) portions of the acini. The more highly folded distal portions of acini show smaller regular cisternae distributed throughout the cytoplasm. The Golgi complex is poorly to moderately developed, and membrane‐bounded secretory granules are absent or sparse. Apocrine secretion predominates in the dorsal lobe.
Dibutyryl cyclic AMP modulation of gap junctions in SW‐13 human adrenal cortical tumor cells
Authors: Murray Sandra A. , Taylor Floyd
Published: February 2005

Cultured human adrenal cortical adenocarcinoma cells (SW‐13) form a confluent monolayer of epithelial like cells when seeded into culture flasks. Following a 24–48 hr nonmitotic period, cells begin to divide and become confluent within a week after seeding at 5×104 cells/cm2. The SW‐13 cells were exposed to dibutyryl cyclic AMP (DbcAMP), cyclic AMP (cAMP), sodium butyrate, and adrenocorticotropin (ACTH). The rate of SW‐13 cell proliferation was measured with a DNA microfluorometric assay, as well as by procedures measuring the incorporation of 3H‐thymidine. In addition, following administration of ACTH and DbcAMP, the fractional area of membrane covered by gap junctions was quantitated with freeze‐fracture electron microscopic techniques. Dibutyryl cyclic AMP at a concentration of 1 × 10−3 M decreased the growth rate of the cell population. There was a corresponding increase in the fractional area of gap junctions found on the cell membrane in 96‐hr DbcAMP‐treated cultures. ACTH (40 mU/ml) exposure failed to produce an increase in the fractional area of gap junctions or to alter the rate of cell proliferation. From these data it can be suggested that elevations in cAMP levels within the cell can be related to both the proliferation of gap junctions and the decrease in cell proliferation in the SW‐13 tumor cell.
Morphometry of feline neutrophil granule genesis
Authors: Fittschen C. , Parmley R. T. , Bishop S. P. , Williams J. C.
Published: February 2005

During neutrophil granule genesis, the formation of primary granules is generally thought to be limited to the promyelocyte stage; whereas synthesis of secondary granules is thought to occur only at the myelocyte stage. This hypothesis was tested morphometrically in feline neutrophils that are known to contain both granule types. Marrow specimens obtained from six cats were stained with peroxidase for identification of neutrophil primary granules and counterstained with periodic acid‐thiocarbohydrazide‐silver proteinate (PA‐TCH‐SP) for identification of secondary granules. By regression analysis using arithmetic models, numbers of cytoplasmic granules in 311 cells were correlated with the degree of nuclear chromatin condensation, which was shown to be an adequate parameter for cell maturation. Promyelocytes and myelocytes had similar mean numbers of peroxidase‐positive granules per unit area. A significant increase (p ≤ 0.0001) in the numbers of peroxidase‐positive granules was noted between the metamyelocyte and the mature neutrophil stage, despite the lack of peroxidase activity in endoplasmic reticulum and Golgi lamellae. By contrast, a significant increase of peroxidase‐negative granules between the metamyelocyte and the mature neutrophil stage was not clearly established with these methods. The increase in peroxidase‐positive granules may indicate continued production of peroxidase‐containing granules and/or redistribution of peroxidase among lysosomal organelles in late feline neutrophils.
Reticular meshwork of the spleen in rats studied by electron microscopy
Authors: Saito Hiroaki , Yokoi Yukio , Watanabe Sumio , Tajima Junko , Kuroda Heroyuki , Namihisa Toshihiko
Published: February 2005

The reticular meshwork of the rat spleen, which consists of both fibrous and cellular reticula, was investigated by transmission electron microscopy. The fibrous reticulum of the splenic pulp is composed of reticular fibers and basement membranes of the sinuses. These reticular fibers and basement membranes are continuous with each other. The reticular fibers are enfolded by reticular cells and are composed of two basic elements: (1) peripheral basal laminae of the reticular cells, and (2) central connective tissue spaces in which microfibrils, collagenous fibrils, elastic fibers, and unmyelinated adrenergic nerve fibers are present. The basement membranes of the sinuses are sandwiched between reticular cells and sinus endothelial cells and are composed of lamina‐densalike material, microfibrils, collagenous fibrils, and elastic fibers. The presence of these connective tissue fibrous components indicates that there are connective tissue spaces in these basement membranes. The basement membrane is divided into three parts: the basal lamina of the reticular cell, the connective tissue space, and the basal lamina of the sinus endothelial cell. When the connective tissue space is very small or absent, the two basal laminae may fuse to form a single, thick basement membrane of the splenic sinus wall. The fibrous reticulum having these structures is responsible for support (collagenous fibrils) and rebounding (elastic fibers).

The cells of the cellular reticulum–reticular cells and their cytoplasmic processes, which possess abundant contractile microfilaments, dense bodies, hemidesmo‐somes, basal laminae, and a well‐developed, rough‐surfaced endoplasmic reticulum, and Golgi complexes, which are characteristic of both fibroblasts and smooth muscle cells–are considered to be myofibroblasts. They may play roles in splenic contraction and in fibrogenesis of the fibrous reticulum. The contractile ability may be influenced by the unmyelinated adrenergic nerve fibers that pass through the reticular fibers.

The three‐dimensional reticular meshwork of the spleen consists of sustentacular fibrous reticulum and contractile myofibroblastic cellular reticulum. This meshwork not only supports the organ but also contributes to a contractile mechanism in circulation regulation, in collaboration with major contractile elements in the capsulo‐trabecular system.
Visualization of the large heparan sulfate proteoglycan from basement membrane
Authors: Laurie G. W. , Inoue S. , Bing J. T. , Hassell J. R.
Published: February 2005

Kleinschmidt spreading, negative staining, and rotary shadowing were used to examine the large form of (basement membrane) heparan suifate proteoglycan in the electron microscope. Heparan suifate proteoglycan was visualized as consisting of two parts: the core protein and, emerging from one end of the core protein, the glycosaminoglydan side chains. The core protein usually appeared as an S‐shaped rod with about six globules along its length. Similar characteristics were observed in preparations of core protein in which the side chains had been removed by heparitinase treatment (“400‐kDa core”) as well as in a 200‐kDa trypsin fragment (“P200”) derived from one end of the core protein. The core protein was sensitive to lyophilization and apparently also to the method of examination, being condensed following Kleinschmidt spreading (length x = 52 nm) and extended following negative staining (length x = 83 nm) or rotary shadowing (length x = 87 nm; 400‐kDa core length x = 80 nm; P200 length x = 44 nm). Two or three glyrosami‐noglycan side chains (length x = 146 + 53 nm) were attached to one end of the core protein. The side chains often appeared tangled or to merge together as one. Thus, the large heparan suifate proteoglycan from basement membrane is an asymmetrical molecule with a core protein containing globular domains and terminally attached side chains. This structure is in keeping with that previously predicted by enzymatic digestions and with the proposed orientation in basement membranes, i.e., the core protein bound in the lamina densa and the heparan suifate side chains in the lamina lucida arranged along the surface of the basement membranes.