bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ultrastructural study of the semicircular canal cells of the frog Rana esculenta
Authors: Oudar Olivier , Ferrary Evelyne , Feldmann Gérard 
Published: February 2005

AbstractThe ultrastructure of the nonsensory cells (dark cells, transitional cells, and undifferentiated cells) of the frog semicircular canal was studied by using transmission electron microscopy in an attempt to correlate the structure with the functions of these epithelial cells. All the nonsensory cells were linked by tight junctions and desmosomes; this suggested that there is little paracellular ionic transport from perilymph to endolymph. In the dark cell epithelium, the apicai intercellular spaces were dilated; in the basal part, numerous basolateral plasma membrane infoldings, containing mitochondria, delimited electron‐lucent spaces. The undifferentiated cells and the transitional cells were devoid of any basal membrane infolding. Surrounding the semicircular canal, very flattened and interdigitated mesothelial cells constituted a thin multilayer tissue which limited the perilymphatic space. The morphological aspect of the dark cells suggests that they may play a role in the secretion and/or in the reabsorption of endolymph, which bathes the apical pole of these cells. The undifferentiated and transitional cells can play a role in the maintenance of the endolymphatic ionic composition because of their apical tight junctions and desmosomes.
Neutrophil lactoferrin content: Variation among mammals
Authors: Barton James C. , Parmley Richard T. , Butler Thomas W. , Williamson Sue , Mackenzie Sandra , Chandler David B. , Blackburn Warren , Heck Louis W. 
Published: February 2005

AbstractLactoferrin (Lf) in blood and/or marrow neutrophils was semiquantified using indirect immunofluorescence technique in nine mammalian species. Neutrophil iron‐binding reactivity (NFeBR), which corresponds primarily to Lf, was also visualized and semiquantified using functional cytochemical (FeNTA‐AF) technique at the light microscopic level in these nine and in an additional fifteen mammalian species, and in selected species at the ultrastructural level. Neutrophil immunoreactive Lf was positively correlated with total cellular and granule content of NFeBR among these nine species, and with previously reported concentrations of neutrophil Lf quantified by radioimmunoassay. Relative levels of Lf in neutrophil extracts from rat, hamster, and human were confirmed using SDS‐polyacrylamide gel electrophoresis and immunoblotting. Relatively high levels of immunoreactive neutrophil Lf and/or NFeBR were observed in carnivores (ten species) and primates (six species). Among rodents (five species), the levels were variable, and the artiodactyls (four species) studied had low levels. These results demonstrate that neutrophil Lf levels vary widely among mammalian species. In addition, FeNTA‐AF technique provides a rapid means of evaluating animals for relative quantities of neutrophil Lf.
Structural heterogeneity within the pulmonary microcirculation of the normal rat
Authors: DeFouw David O. 
Published: February 2005

AbstractExtra‐alveolar microvessels of the rat were described previously as nonmuscular, partially muscular, and muscular (Hislop and Reid, 1978). Based on these structural criteria, the present morphometic results present evidence that mean thickness of the endothelium was significantly greater in the muscular microvessels than in each of the other microvessel categories. The percentage of endothelial surface occupied by attenuated segments (20–30 nm maximal thickness) was greatest in the nonmuscular and partially muscular microvessels. Mean plasmalemmal vesicle diameters were consistent throughout the microvascular units. Vesicle numerical densities, however, were significantly greater in the alveolar capillary endothelium than in endothelia of the nonmuscular, partially muscular, and muscular microvessels. Endothelial vacuoles (diameters greater than 150 nm) were not observed in either the capillaries or the nonmuscular microvessels. Mean diameters and numerical densities of vacuoles observed in endothelia of the partially muscular and muscular microvessels were, however, statistically similar. Subclassification of the partially muscular and muscular microvessels by ultrastructural characteristics as arterioles or venules (Rhodin, 1978; Michel, 1982) served to identify greater numerical densities of vesicles in the endothelium of venules than that of the arterioles. As expected, mean thicknesses of the periendothelial connective tissue spaces varied directly with the relative muscularity of the respective microvessels. Based upon the morphometric data presented in this study, future investigations of pulmonary microvascular functions should include considerations of the observed regional variations of endothelial cell ultrastructure.
Endocytosis of parotid salivary proteins by striated duct cells in streptozotocin‐diabetic rats
Authors: Lotti Lavinia V. , Hand Arthur R. 
Published: February 2005

AbstractSalivary gland striated duct cells play an important role in the modification of primary saliva by secretion and reabsorption of electrolytes, and secretion of glycoproteins. Recent observations have shown that in the rat parotid gland these cells are able to internalize exogenous proteins, e.g., horseradish peroxidase and ferritin, from the ductal lumen. In rats made diabetic by injection of streptozotocin, dense vacuoles and crystalloids are present in the apical cytoplasm of parotid striated duct cells. In this study we utilized electron microscopic immunocytochemistry to determine if these vacuoles and crystalloids contain acinar secretory proteins. At various times after induction of diabetes by streptozotocin (65 mg/kg), the parotid glands were fixed in a glutaraldehyde‐formaldehyde mixture, postfixed in OsO4, and embedded in epoxy resin. Thin sections were immunolabeled with antibodies to protein B1 (Ball et al., 1988) and α‐amylase (Baum et al., 1982) using a modification of the Protein A‐gold technique (Bendayan and Duhr, 1986). With antibody to B1, label was localized in the secretory granules of acinar and intercalated duct cells of both normal and diabetic rats. In striated duct cells of diabetic rats, label was present over the electron‐dense vacuoles but not over the crystalloids. Since crystalloids appear to form within the vacuoles, their lack of reactivity may indicate degradation of the internalized protein. The same distribution of label was found with antibody to amylase except for the intercalated duct granules, which were unlabeled in both control and diabetic animals. These results demonstrate that striated duct cells take up salivary proteins from the lumen and that the endocytosis of some secretory proteins from the saliva may be a significant function of these cells in certain pathological conditions.
Origin and propagation of elastogenesis in the developing cardiovascular system
Authors: Rosenquist Thomas H. , McCoy Judy R , Waldo Karen L. , Kirby Margaret L. 
Published: February 2005

AbstractEctomesenchyme derived from cardiac neural crest is critical to aorticopulmonary septation in the heart. However, any unique contribution of the cardiac ectomesenchyme to the extracellular matrix of the conotruncus has not been demonstrated previously.In this study the chronology and topography of soluble tropoelastin (STE) and the aldehyde‐rich protein (ARP) of the elastic connective tissues have been examined in the chick embryo, stages 21–38, and in the quail‐chick chimera, stages 24–35 (quail neural fold grafted onto a chick embryo). STE was located with immunofluorescence histochemistry, and ARP with Schiff's reagent. With these procedures prevenient site of elastin synthesis are observed readily.The results show that the myocardium proper appears to have a role in the instigation of elastogenesis and in elastic fiber orientation; that the mesenchymal cells whose matrix contains elastic fibers are ectomensenchymal, of neural crest origin; and that elastin is deployed in an orderly proximal‐distal sequence.It is hypothesized that elastogenesis is a critical event in aorticopulmonary septation.
Acute and chronic reactions of dental sensory nerve fibers to cavities and desiccation in rat molars
Authors: Byers M. R. , Närhi M. V. O. , Mecifi K. B. 
Published: February 2005

AbstractWe have studied the effects of air drying of exposed, acid etched dentin on the sensory innervation of rat molars. In the acute series of experiments, trigeminal nerve fibers were labeled by axonal transport of radioactive protein prior to the dentin exposure and desiccation, the anesthetized rats were fixed by aldehyde perfusion 10 min later, and the teeth were prepared for autoradiography. The results confirmed the hydrodynamic theory by showing outward movement of labeled nerve material in response to dentinal drilling and desiccation. It also showed that some odontoblasts could be separated from the dentinal nerve fibers. In the chronic series, teeth were injured 25 h, 5–7 days, or 21 days prior to fixation and nerves were labeled during the last 24 hours; the surviving vital nerve fibers were evident because of their axonal transport of the radioactive label. In that series, sensory nerve fibers were found to have been lost from areas with newly‐formed reparative dentin, or from dentinal tubules that had lost their odontoblasts. In the teeth injured 25 h, 5–7 days, or 21 days earlier, an abnormal nonneuronal labeling occurred 0.2–0.3 mm into injured dentin. Our results are discussed in relation to the hydrodynamic theory, nerve‐odontoblast interactions, differences between shallow and deep cavity injuries, altered nerve location in response to pulpal or dentinal injury, and characteristics of the pulp‐dentin border.
Angiogenesis in the developing corpus luteum of pregnant rats: A stereologic and autoradiographic study
Authors: Meyer Geoffrey T. , McGeachie John K. 
Published: February 2005

AbstractWithin the adult mammalian ovary, angiogenesis is associated with development of the corpus luteum (CL). In this study, developing luteal tissue was examined to determine whether its vascularization involves endothelial cell replication and to what extent this proliferation contributes to forming new capillaries. Five rats each at 12, 24, 36, 48, 60, 72, 84, and 96 hr of gestation were given a subcutaneous injection of tritiated thymidine (specific activity 5 Ci/M; 1 uCi/g body weight). One hour later they were anesthetised with sodium pentobarbitone, and the left ovary was processed for light microscopy. Sections were cut through each ovary until three newly formed CL were recognized; a 1‐μ section was taken from the maximum diameter of each CL and processed for autoradiographic demonstration of thymidine labeling in endothelial cell nuclei. The same sections were also examined with stereological techniques to quantitate growth of the vascular compartment. The results show that 36.1 ± 5.7% of endothelial cells of invading capillary sprouts divide within 12 hr of ovulation; at 24 hr, 29.0 ± 2.8% are dividing. Within 12 hr after ovulation, blood vessels occupied 5.9 ± 1.4% of the peripheral space of the ruptured follicle but only 1.6 ± 0.5% in the center. However, by 36 hr these respective values were 9.3 ± 1.6% and 8.4 ± 1.9% A further peak in endothelial‐cell replication (31.2 ± 5.4%), early on the 3rd day of gestation, corresponded to the very extensive anastomoses within the capillary bed established between this time (13.6% vascularity) and late on the 4th day (about 23%). We conclude that replication of endothelial cells from capillary sprouts accounts for substantial angiogenesis in the developing CL. Labeling in endothelium of the developing CL and the capsule surrounding the CL were greater than in CL of previous cycles and vessels within the ovarian stroma. This finding supports the view that there may be some local control of endothelial‐cell replication.
Development of mitochondrial helical sheath in the middle piece of the mouse spermatid tail: Regular dispositions and synchronized changes
Authors: Otani Hiroki , Tanaka Osamu , Kasai Kei‐Ichiro , Yoshioka Takafumi 
Published: February 2005

AbstractMorphologic changes in the development of the mitochondrial helical sheath in the mouse spermatid tail were examined with the scanning electron microscope (SEM) using the osmium‐DMSO‐osmium method and classified into several stages. During late spermiogenesis, spherical mitochondria gathered around the forming spermatid tail. The shape of these mitochondria gradually changed from spheroid to long and rod‐like. Mitochondria first were arranged in four longitudinal rows (stage 1) that twisted dextrally, and the mitochondria began to stagger (stage 2). They became elongated and arranged into a staggered pattern; they then attached to each other in an end‐to‐end fashion to form a sinistral double helix around the core of the axoneme (stage 3). These end‐to‐end contacts were observed in every second gyre on the four lines surrounding the core of the axoneme at stage 3. Mitochondria further elongated and end‐on touching appeared with every third gyre on the five longitudinal lines that surround the core of the axoneme (stage 4). The direction of the helix, always sinistral, was clearly discernible only in the later stages. Disposition of the mitochondria in the spermatid tail was regular throughout development, which indicates that these mitochondria elongate simultaneously and also at the same rate. On any given cracked surface of the seminiferous tubule, spermatid tails with the same stage of mitochondria predominantly were observed. This ultrastructural finding appears compatible with the histologic synchronism, (termed the “wave”) in differentiating germ cells.
Origin of aortic cell clusters in the chicken embryo
Authors: Olah Imre , Medgyes J. , Glick Bruce 
Published: February 2005

AbstractIn 3‐day‐old embryos the aortic cell clusters formed two parallel ridges in the ventrolateral part of the aorta. The border of the somato‐ and splanch‐nopleures close to the aorta showed a very intensive cell proliferation and a cell emigration up to the aorta. This cell flow and the bilateral appearance of the intraaortic ridges suggested that the aortic cell clusters originated from the coelomic epithelium. This intraembryonic hemopoietic stem cell formation from the splanchnopleure was comparable to that of the blood island formation in the yolk sac from extraembryonic splancnopleure. The appearance of the white blood cells and definitive erythrocytes with adult‐type hemoglobin was preceded by the aortic cell clusters. We concluded that the stem cells of the adult‐type blood developed from the aortic cell clusters whereas the blood islands of the yold sac may contribute only the primitive red blood cells.
Extragonadal distribution of primordial germ cells in the early chick embryo
Authors: Nakamura Masao , Kuwana Takashi , Miyayama Yukihiko , Fujimoto Toyoaki 
Published: February 2005

AbstractChick primordial germ cells (PGCs), after separation from the endoderm in early embryonic development, temporarily circulate via the blood vascular system and finally migrate into the gonadal anlagen. It has been noted by some authors that some PGCs are present in extragonadal sites in some vertebrates. In the present study, we examined the distribution and localization of PGCs in extragonadal sites in the chick embryo. PGCs were identified by periodic acid‐Schiff staining with light microscopy. In embryos at stages 20–24 (PGCs are in the settlement stage in the gonadal primordium), approximately 20% of the total number of PGCs were observed in extragonadal regions. Approximately 90% of these ectopic PGCs were found in the head, mainly in the mesenchyme surrounding the neural tube. Even at stage 14 when PGCs were usually circulating in the blood vessels, some of the PGCs had emerged from the blood vessels and were detected in the extragonadal site. The pattern of distribution of ectopic PGCs in the head area is probably attributed to the earlier, dominant development of the capillay network, and to the sluggish capillary blood flow in that region, which allows intravascular PGCs to escape into the tissue.
Fiber sizes and histochemical characteristics of the rectus abdominis muscle of the rabbit under conditions of pregnancy and mechanically induced stress
Authors: Costerbosa G. Lalatta , Barazzoni A. M. , Lucchi M. L. , Bortolami R. 
Published: February 2005

AbstractHistochemical properties and muscle fiber diameters of the rectus abdominis (RA) muscle of the female rabbit were compared with those of RA muscle of (1) pregnant females at term of pregnancy (30 days); (2) pregnant females in which the stretch on the abdominal wall natural to pregnancy was artificially prolonged with a 40‐day period of intraabdominal appliance; (3) virgin females subjected to intraabdominal appliance for 30, 45, 60, and 70 days. The RA muscle of the control female rabbits is composed of 29.73% type I, 12.13% type IIA, 57.59% type IIB, and 0.54% type IIC fibers. The stimulation on RA muscle due to either normal pregnancy or implant in virgin females provoked changes in muscle fiber diameters only; with the normal pregnancy plus the subsequent period of mechanical stimulation, changes occurred not only in muscle fiber diameters, but there was also a significant increase in the percentage of type I fibers and a concomitant decrease of type IIA and IIB fibers.The fiber‐type pattern in the RA muscle of male and female rabbit also was compared. The RA muscle of the male rabbit showed more type IIA and less Type IIB fibers than found in that of the female. Type I fibers were larger in the female, but type IIA fibers were larger in the male. In addition, male rabbits also were subjected to 30, 45, 60, and 70 days of RA muscle stimulation by means of an intraabdominal appliance to ascertain if the influence of such stimulation upon the RA muscle differed between the two sexes. Some differences in the response of the male RA muscle were noted.
Quantitation of structural features characterizing weight‐ and less‐weight‐bearing regions in articular cartilage: A stereological analysis of medical femoral condyles in young adult rabbits
Authors: Eggli Peter S. , Hunzinker Ernst B. , Schenk Robert K. 
Published: February 2005

AbstractThe structural organization of articular cartilage from the medial femoral condyle of young adult rabbits has been examined after processing according to an improved fixation procedure. By using recently developed stereological methods, a quantitative analysis of chondrocyte number, surface area, volume, and matrix volume per cell was carried out in the light microscope; at the electron microscopic level, quantities of cytoplasmic components within chondrocytes (including organelles) were estimated. These measurements were made for each of the four zones from the (articular cartilage) surface down to the tidemark, and the results (for each zone) were compared between weight‐ and less‐weight‐bearing regions.In general, articular cartilage revealed considerable heterogeneity in structure throughout its depth. The number of cells per unit volume is maximal beneath the surface and decreases towards the tidemark. The size of chondrocytes, and the mean matrix volume surrounding each, increases from the surface toward the deeper zones. Comparison between weight‐ and less‐weight‐bearing regions reveals striking differences. The numerical volume density of cells in the superficial zone of regions bearing high physiological load is less than half of that in less‐weight‐bearing regions, chondrocyte death being principally responsible for this reduction. A comparison between the midzones of weight‐ and less‐weight‐bearing areas reveals that the former is characterized by a decrease in cell density and an approximately threefold increase in cell size in relation to the latter. The increase in cell volume is attributable principally to an accumulation of intermediate filaments and glycogen particles, and represents an adaptation to increased functional requirements. Near the tidemark, numerical volume densities of chondrocytes in both weight‐ and less‐weight‐bearing locations are similar, but the larger cell size in the former still persists.
Budding of small vesicles from the rough‐surfaced endoplasmic reticulum in secretory ameloblasts of rat molar tooth germs
Authors: Matsuo Saburou , Takano Yoshiro , Wakisaka Satoshi , Ichikawa Hiroyuki , Nishikawa Shinji , Akai Michio 
Published: February 2005

AbstractThe budding of small vesicles from the rough‐surfaced endoplasmic reticulum (rER) was examined in the secretory ameloblast of rat molar tooth germs by ordinary fixation or prolonged osmium fixation. The budding of small vesicles from the rER was observed not only at the special region (transitional region) of the rER system, which abutted on the cis‐face of the Golgi apparatus, but also at other regions of the rER in the secretory ameloblast. Small vesicles (presumed to be transitional vesicles) were adjacent to the rER, which also showed budding of vesicles. After prolonged osmium treatment, osmium deposits appeared in small vesicles, as well as in the cisternae of the cis saccule of the Golgi apparatus. Small vesicles containing osmium deposits were located at various regions of the cell, including the cis‐face of the Golgi apparatus. These findings indicate that the budding of small vesicles from the rER is not restricted to the transitional region of the rER system of the secretory ameloblast, but is found at various regions of the cell. This indicates that newly synthesized proteins may be transferred from the rER cisternae to the transitional vesicles not only in the transitional region of the rER system adjacent to the Golgi apparatus, but also in other regions of the secretory ameloblast.
A survey by scanning electron microscopy of the extracellular matrix and endothelial components of the primordial chick heart
Authors: Drake Christopher J. , Jacobson Antone G. 
Published: February 2005

AbstractScanning electron microscopy was used to study the morphogenesis of the primitive embryonic chick heart (stage 5 late primitive streak through stage 9+). Components of the developing heart (myocardium, endocardial endothelium, and extracellular matrix) were viewed from the ventral surface after removal of the endoderm.The myocardial component of the heart can first be seen by light microscopy at stage 5 as two darker oval‐shaped areas located on either side of the embryonic axis in the cranial region of the embryo. Scanning electron microscopy demonstrates that as early as stage 6 an area of extracellular matrix, enriched in comparison to more lateral and medial splanchnic mesoderm, can be identified ventral to the myocardial primordium.As heart formtion progressed we observed primordial endothelial elements in the splanchnic mesoderm lateral to the myocardial primordia. By late stage 7 these lateral primordial elements had anastomosed into small, loose plexuses. This process of anastomosis progressed rapidly, and by stage 8 the entire cranial surface of the myocardial primordium was covered with vascular plexuses. By late stage 8 the progressive fusion of these plexuses resulted in the formation of large multiple tubular elements near the midline. More medially the fusion of tubular elements resulted in a continuous endothelial sheet at the midline.