bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ultrastructure of the choroid plexus epithelium of pigeons treated with drugs. II. Effect of cytochalasin D and colchicine
Authors: Koshiba Kimikazu 
Published: February 2005

AbstractA remarkable projection of bleblike protrusions, the expulsion of organelles into the protrusions formed on the apical surface, and the separation into the ventricular lumen of these protrusions was the general cellular response of choroidal epithelial cells to intravenous injection of cytochalasin D (CD). The compact microfilament mass and agglomeration of microtubules at the base of the cluster of protrusions reflect the results of cell contraction and displacement of microfilaments induced by CD.In earlier stages after intravenous injections of colchicine, an obvious increase in the number of varioussized vesicles, vacuoles, and lysosomes in the Golgi region was detected. In the later stages, these organelles were seen to accumulate in the basal portion of the epithelial cells. These changes were accompanied by an increase in vacuoles and the disorganization and displacement of the Golgi complex, and they coincided with a decrease in the number of microtubules in apical and basal cytoplasm. These findings suggest that the action of colchicine results in destruction of the three‐dimensional architecture between cytoskeletal network and cell organelles.The present results suggest that the cytoskeletal network plays a role in the spatial coordination of the three‐dimensional architecture of cell organelles. The study also indicates that the structural differences in the ventricles of the choroid plexus in drug‐treated pigeons are manifestations of regional functional specialization in different parts of the ventricular system.
Lung growth of the turkey, Meleagris gallopavo: II. Comparison of two genetic lines
Authors: Timmwood K. I. , Hyde D. M. , Plopper C. G. 
Published: February 2005

AbstractComparisons of lung growth in two genetic lines of turkeys, one unselected and one selected for increased body mass, were used to evaluate the lung's alteration in structure with changes in body form or physiology. Seventy‐two male turkeys, 36 genetically selected for early rapid growth and large pectoral musculature, and 36 unselected birds, were killed at 12 different ages to compare lung growth in the two lines. Body weights and lung volumes were determined. A three‐level cascade sampling system was used to prepare lung tissue for qualitative and quantitative observation by light microscopy. Allometric equations describing growth of lung volume and lung compartments relative to body weight in two phases (tissue proliferation and equilibrated growth) were compared between lines of turkey for differences in slopes or intercepts. Means of data for 112‐ and 420‐day‐old birds were also compared.There were no qualitative histological differences observed between lungs of the two lines of turkey, yet there were morphometric differences in lung growth relative to body weight. During equilibrated lung growth, there was less rapid growth of air and blood capillary volumes and surfaces relative to body weight in the selected than in the unselected turkey. The gasexchange compartment did not enlarge concomitant with the large increase in muscle mass of the selected turkeys, while large‐vessel volume and small‐airway volume grew similarly to body weight in both turkey lines. We conclude that the lung of the selected line of turkeys did not show an enlarged gas‐exchange compartment relative to the greater body muscle mass, but it did show enlarged vessels and conducting airways.
Circadian modification of ethanol damage in utero to mice
Authors: Sauerbier Ingrid 
Published: February 2005

AbstractThis study evaluates the ethanol toxicity for fetal development at different circadian stages. Pregnant mice were given a single intraperitoneal ethanol injection on day 7, 8, or 10 of gestation at one of four circadian stages (0700, 1300, 1900, or 0100 hr). The dams were killed on the day before term (day 18). Prenatal exposure to ethanol resulted in an increased number of resorptions, reduced fetal body weight, and produced an increased incidence of external alterations. The severity of damage was related to the dose, the period of gestation, and particularly to the circadian stage at the time of treatment. Ethanol had the greatest effect on the embryo of a mouse when administered at the mid‐dark span. Consequently exposure to a single dose of ethanol at one time or another along the 24‐hr time scale during organogenesis has important implications for the substantially increased risk.
Structure and growth activities of the mandibular condyle in monkeys (Macaca fascicularis): II. Synergistic behavior of cell dynamics and metabolism
Authors: Luder H. U. 
Published: February 2005

AbstractThe mandibular condyles of eight growing male monkeys (Macaca fascicularis) were analyzed by using a combination of radioautographic and morphometric techniques. This was done with the aim of examining the dynamics in the structure and growth activities of the articular tissue covering as well as of the subchondral zone of erosion. The animals received 1 mCi/kg body weight 3H‐proline 24 hr and 0.5 mCi/kg body weight 3H‐thymidine 3 hr prior to death. Their age was estimated on the basis of skeletal maturation as recorded from radiographs of the hand and wrist. Consistently, (1) the proliferative activity in the intermediate layer, (2) the rates of cell turnover and growth of chondroblasts and chondrocytes, (3) the rates of extracellular matrix production in the intermediate and chondral layers, as well as (4) the resorptive and (5) appositional activities in the zone of erosion were characterized by an in‐concert behavior. This behavior suggests a general synergistic control of the various cell dynamic and metabolic processes affecting the rate of normal condylar growth.
Fourth ventricular floor in human embryos: Scanning electron microscopic observations
Authors: Tanaka Osamu , Otani Hiroki , Fujimoto Katsukuni 
Published: February 2005

AbstractThe ultrastructural surface features of the normal fourth ventricular floor of seven human embryos ranging from Carnegie stage 14 to stage 19 (crown‐rump length: 7.6–16.2 mm) were examined by using scanning electron microscopy (SEM). Low‐power SEM views showed the median sulcus, sulcus limitans, and neuromeres, transient structures characteristic of the earlier embryonic period. High‐power SEM observation revealed supraependymal cells (SE cells) and supraependymal fibers (SE fibers) which exhibited a characterisitc localization, as well as generalized surface‐membrane modifications such as microvilli and cilia. SE cells could be classified into two major groups. The type 1 SE cells seem to possess neuronal functions, as deduced from morphological similarities to their counterparts in adults and the specialized distribution closely related to neuromeres. The type 2 SE cell morphologically resembled the phagocytic SE cell described in related literature. SE fibers ran a course either rostrocaudally in the median sulcus or mediolaterally on the neuromeres, most frequently near the interneuromeric cleft; they made contact with type 1 SE cells and ependymal surface modifications and then penetrated the ependymal layer.
Patterns of organelle distribution in mouse embryos during preimplantation development
Authors: Batten Bruce E. , Albertini David F. , Ducibella Tom 
Published: February 2005

AbstractWe have evaluated the distribution of mitochondria and acidic organelles using, respectively, the specific vital fluorescent dyes rhodamine 123 and acridine orange during preimplantation embryonic development in the mouse. Under conditions used to visualize organelles in living embryos, staining with either dye was found to have no effect on either the rate or extent of in vitro development of five‐ to eight‐cell embryos up to the blastocyst stage. Mitochondria were randomly distributed throughout the cytoplasm and located around nuclei in blastomeres of uncompacted embryos. During compaction, mitochondria initially reorganized to the blastomere cortex; however, these organelles were later confined to the perinuclear region in the trophectoderm (TE) of expanded blastocysts. Acidic organelles were randomly distributed in the cytoplasm of uncompacted embryos, but following compaction, they were concentrated in cortical and perinuclear locations. Moreover, in TE cells of expanded blastocysts, acidic organelles were found exclusively in a tight perinuclear pattern. Microtubules and microfilaments in TE cells were localized in fixed embryos stained with antitubulin antibodies and rhodamine phalloidin, respectively; these structures were found primarily in the cortical cytoplasm at areas of cell‐cell contact and secondarily in a perinuclear location. Thus mitochondria and acidic organelles undergo stage‐specific redistributions from a diffuse or cortical pattern at the eight‐cell stage to a tight perinuclear localization in the TE. We conclude that the polarized distributions of some organelles and cytoskeletal proteins during compaction may not be reliable permanent markers of the mature TE.
The Golgi apparatus in the acinar cells of the developing embryonic pancreas: II. Localization of lectin‐binding sites
Authors: Pavelka Margit , Ellinger Adolf 
Published: February 2005

AbstractThe reaction patterns of the Golgi apparatus following staining with the lectins concanavalin A (ConA), Ricinus communis I agglutinin (RCA I), and Helix pomatia lectin (HPA) were studied in the pancreas acinar cells of rat embryos in the course of cell differentiation from day 13 through day 20 of gestation. The binding reactions were localized by means of pre‐embedment incubation of 10‐μm‐thick cryosections of pancreas tissue, prefixed in a mixture of 4% formaldehyde/0.5% glutaraldehyde, using horseradish peroxidase for electron microscope visualization.ConA, which preferentially binds to α‐D‐mannosyl residues, consistently stained the cisternae of the cis Golgi side. The majority of the stacks also showed ConA staining of medial cisternae. The reaction of the trans side was variable; in each stage of development, the cisternae of the trans Golgi side either were devoid of labeling or appeared intensely stained. The reactions obtained with RCA I, which recognizes terminal β‐D‐galactosyl residues, changed in the course of cell differentiation; in the protodifferentiated and early differentiated states, the system of “rigid lamellae,” located at the trans side of the Golgi stacks, was intensely labeled, but became unreactive after production of secretion granules had started, the reaction then being restricted to the stacked saccules. In regard to the Golgi stacks in each of the developmental stages, RCA I binding sites either were confined to the trans cisternae, or, in addition, were found distributed across elements of the medial and cis compartments. Frequently, the reaction intensities increased in the cis‐to‐trans direction. The Golgi patterns apparent after the staining with HPA, which interacts with α‐N‐acetyl‐D‐galactosaminyl residues, were variable at all stages of differentiation; the reactions either were restricted to the cis and/or medial cisternae, or expanded across the entire stack of saccules.These results illustrate that the distribution across the Golgi stacks of binding sites for ConA, RCA I, and HPA is variable; none of the three lectins tested can be considered to be a probe for specifically labeling subsections of the Golgi stacks in developing pancreas acinar cells.
Transendothelial transport (transcytosis) of iron‐transferrin complex in the rat liver
Authors: Kishimoto Takumi , Tavassoli Mehdi 
Published: February 2005

AbstractTo determine the transport pathway of iron‐transferrin complex (Fe‐TF) into the hepatocyte, we labeled Fe‐TF with colloidal gold and perfused rat liver through the portal vein with this probe under different conditions. The tissue was then studied by transmission electron microscopy. At a cold temperature (∼ 4°C), the probe bound to the luminal surface of sinusoidal endothelium without internalization. The binding was limited to the endothelium and there was no binding to Kupffer cells or hepatocytes. The binding was inhibitable in the presence of excess soluble Fe‐TF, indicating the specificity of the bindings. At 37°C the probe was internalized via a system of coated pits and vesicles. Morphometric analyses of the temporal sequence of events suggested that the probe was transported, in part, across the endothelium via a system of tubules and vesicles and externalized on the abluminal side via a system of coated pits. The probe was then taken up by hepatocytes. Only minimal uptake was noted when gold‐labeled bovine serum albumin was used either at the low temperature or at 37°C. The findings suggest that the liver uptake of Fe‐TF complex by hepatocytes is a transendothelial phenomenon (transcytosis).
Synthesis and migration of 3H‐fucose‐labeled glycoproteins in the retinal pigment epithelium of albino rats, as visualized by radioautography
Authors: Haddad A. , Bennett G. 
Published: February 2005

Abstract3H‐fucose was injected into the vitreous body of the eye(s) of 250‐gm rats, which were then killed by means of an intracardiac perfusion with glutaraldehyde after intervals of 10 min, 1 and 4 hr, and 1 and 7 days. The eyes were removed and further fixed, and pieces of retina were processed for light and electron microscope radioautography. Light microscope radioautography showed that the pigment epithelial cells actively incorporated 3H‐fucose label. The intensity of reaction peaked at 4 hr after injection of the label and then slowly declined. Quantitative electron microscope radioautography revealed that, at 10 min after 3H‐fucose injection, over 70% of the label was localized to the Golgi apparatus, indicating that fucose residues are added to newly synthesized glycoproteins principally at this site. With time the proportion of label associated with the Golgi apparatus decreased, but that assigned to the infolded basal plasma membrane, the apical microvilli, and various apical lysosomes increased. These results indicate that in retinal pigment epithelial cells newly synthesized glycoproteins continuously migrate from the Golgi apparatus to lysosomes and to various regions of the plasma membrane. In this case, the membrane glycoproteins may play specific roles in receptor functions of the basal plasma membrane or phagocytic activities at the apical surface. Very little label migrated to Bruch's membrane, indicating either a very slow turnover or a paucity of fucose‐containing glycoproteins at this site.
Heterogeneity of spindle units in the cat tenuissimus muscle
Authors: Kucera Jan , Walro Jon M. 
Published: February 2005

AbstractThree tandem spindles and their nerve supplies, reconstructed by light microscopy of serial transverse sections of the cat tenuissimus muscle, were compared to single spindle units. Each tandem spindle consisted of one large unit containing a dynamic bag1, a static bag2, and several static chain fibers (b11b2c unit) linked by the bag2 fiber to a small unit containing only a bag2 and chain fibers (b2c unit). Most features of primary afferents, secondary afferents, and motor neurons were qualitatively and quantitatively similar in both single and tandem b1b2c units. However, b1b2c units of tandem spindles had a lower density of skeletofusimotor innervation than did single b1b2c spindles. The 2c spindle units differd greatly from single or tandem b1b2c units. The 2c spindle units had fewer intrafusal fibers and incoming axons than either the tandem or single b1b2c units. The motor innervation of b2c units was typified by nonselective γ axons that coinnervated both bag2 and chain fibers, in contrast to the regular occurrence of both selective and nonselective motor axons in b1b2c spindle units. The afferent located at the equator of 2c units differed in size, branching pattern, and intrafusal distribution of its ending from both the primary and secondary sensory axons of b1b2c units and, therefore, might represent a third category of spindle afferent. Thus, cat tenuissimus muscles contain three types of spindle units that differ in the number and organization of muscular and neural elements. These differences in structure and neural organization among tenuissimus spindle units may be a source for generation of different sensory signals in response to common mechanical or fusimotor stimuli.
Nuclear origins of brainstem reticulocortical systems in the rat
Authors: Newman Donald B. , Liu Rita P. C. 
Published: February 2005

AbstractStereotaxic injections of 5% Fast Blue or 1% horseradish peroxidase‐wheat germ agglutinin conjugate (HRP‐WGA) were made into various cytoarchitectonic or functional regions of the cerebral cortex of anesthetized adult albino or hooded rats. Sections through the brainstems of these animals were then scrutinized for the presence of retrogradely labeled neurons. The data generated by this study indicate that at least 33 distinct nuclei or subnuclei within the brainstem reticular formation of the rat project directly to the cerebral cortex. More than half of these ascending reticulocortical systems are probably aminergic. The strongest reticulocortical projections emanate from presumed aminergic reticular‐cell groups located at isthmic levels: specifically, the rostral serotonin‐containing cell groups, as well as the noradrenergic locus coeruleus. However, relatively strong direct reticulocortical projections also originate from lower medullary cell groups which are probably catecholaminergic. Moderately strong reticulocortical projections emanate from cholinergic cell groups located at isthmic levels (the pars compacta of the pedunculopontine nucleus and the X area of Sakai). The most surprising finding in this study was that the classic isodendritic, nonaminergic central core of the brainstem gives rise to direct reticulocortical projections. The ventromedial areas of the medullary brainstem reticular formation give rise to the strongest nonaminergic ascending reticular projections, but all levels of the classic isodendritic reticular core give rise to direct reticulocortical projections. As a whole, cortically projecting reticular neurons are mostly small (10–25 μm in greatest diameter) or medium sized (26–35 μm in greatest diameter) neurons.Previous studies have shown that many of the cortically projecting reticular nuclei also project to the spinal cord, and, within these nuclei, reticulocortical neurons often strongly resemble their reticulospinal counterparts with respect to details of neuronal morphology. This in turn suggests that some reticulocortical neurons may also project to spinal levels.
The osteopetrotic rabbit: Skeletal cytology and ultrastructure
Authors: Marks Sandy C. , MacKay Carole A. , Seifert Mark F. 
Published: February 2005

AbstractThe lethal, autosomal recessive osteopetrotic mutation in the rabbit, osteosclerosis (os/os), has recently been made available for experimental investigation. We have examined the cytology and ultrastructure of skeletal cells in mutants and report abnormalities in osteoblasts, osteocytes, and osteoclasts. Mutant osteoclasts lack a well‐defined ruffled border and show few morphological signs of bone resorption. Osteoblasts in mutants form bone in neonatal life but show signs of degeneration by 2 weeks after birth. Mutant osteoblasts and osteocytes contain large, electron‐dense cytoplasmic inclusions. External surfaces of mutant long bones show no evidence of bone resorption by scanning electron microscopy, and fibrosis of intertrabecular spaces is a prominent feature in mutants. These data, considered with recent evidence that the functions of osteoblasts and osteoclasts are interrelated, suggest that reduced bone resorption, a characteristic feature of osteopetrosis, may be related to osteoblast incompetence in this mutation.
Changes in leydig cell activity during the annual testicular cycle of the bat Myotis lucifugus lucifugus: Histology and lipid histochemistry
Authors: Gustafson A. W. 
Published: February 2005

AbstractChanges in Leydig cell histology and testicular sudanophilic lipids were examined in relation to spermatogenic activity in the bat Myotis lucifugus lucifugus (Chiroptera: Vespertilionidae) throughout the annual cycle in the northeastern United States. These changes were correlated with annual variations in plasma testosterone concentrations which have recently been described for this species. Gametogenic activity occurred during the months of May‐August when bats were metabolically most active. During hibernation (October‐April), when sperm are stored in the epididymides, and accessory glands are hypertrophic, the seminiferous tubules were at rest, and the germinal epithelium was reduced to reserve spermatogonia and Sertoli cells. Based on their structure and cyclic pattern of sudanophilic lipids, Leydig cells exhibited a pattern of activity that closely paralleled that of the seminiferous epithelium. On renewal of spermatogenesis in spring, Leydig cells became hypertrophied and accumulated lipid inclusions. These inclusions, seen as vacuoles in plastic sections and sudanophilic droplets in frozen sections, reched maximal accumulations in late June. In late July and during August, when peak testosterone levels occur in blood, lipid droplets were dramatically depleted, and Leydig cells were weakly sudanophilic. In September, when testosterone titers return to low baseline levels, Leydig cells had regressed but exhibited a marked increase in sudanophilic inclusions which appeared to be mostly lipofuscins. During the ensuing mating and hibernation periods, Leydig cells were involuted and filled with lipofuscins. During the periarousal period, however, Leydig cells became weakly Sudan‐positive while many large, intensely sudanophilic cells were scattered throughout the interstitium. In electron micrographs these cells were identified as macrophages. They appear to play an important role in the annual testicular cycle by phagocytizing the residues of Leydig cell involution in preparation for a new steroidogenic cycle. Seasonal changes in lipid inclusions were also observed in the seminiferous tubules. In addition, the relationship of the Leydig cell cycle to androgen action and the accessory organs in this bat is discussed.
Plasma membrane structure of bat spermatozoa: Observations on epididymal and uterine spermatozoa in Myotis lucifugus
Authors: Hoffman L. H. , Wimsatt W. A. , Olson G. E. 
Published: February 2005

AbstractPlasma membrane structure of bat spermatozoa was examined utilizing electron microscopy of thin sections and freeze‐fracture replicas. Notable membrane features observed in replicas from cauda epididymal spermatozoa included specialized particle aggregates at the junction between the acrosomal and postacrosomal region of the head (a membrane structure not previously described in mammalian spermatozoa) and another row of rod‐like particles just anterior to the posterior ring. Both of these specializations in fractured plasma membranes correspond with regions where the membrane is closely apposed to underlying structures when viewed in thin sections. The postacrosomal sheath appears to be composed of an array of longitudinally oriented filamentous components. Characteristic ordering of intramembranous particles was also noted in replicas from the midpiece region and the annulus. Major changes in plasma membrane structure were not seen in spermatozoa stored in the female reproductive tract; however, the appearance of linear particle aggregations in the principal piece membrane was noted. No evidence was obtained to suggest that an acrosome reaction had occurred in spermatozoa stored in females.