bluuebunny/crossref_metadata_2025_split huggingface dataset:
Inhibition of membrane bone formation by vitamin A in the embryonic chick mandible
Authors: Tyler Mary S. , Dewitt‐Stott Rachel A. 
Published: February 2005

AbstractEmbryonic chick mandibles (Hamburger and Hamilton [HH] stages 17–25) were cultured in the presence of various concentrations of vitamin A to determine the effect of hypervitaminosis A on membrane bone formation. In normal development, the mandible differentiates a centrally located Meckel's cartilage surrounded by membrane bones. Mandibles cultured without added vitamin A differentiated normally, though the timing of differentiation was retarded from that in ovo. Treatment with vitamin A interfered with skeletogenesis to varying degrees depending upon the initial age of the explant and the concentration of vitamin A. At low concentrations of vitamin A (1 μg/ml), neither cartilage nor membrane bone formed in young explants (HH stage 17), whereas cartilage formed in 78% and membrane bone in 11% of older explants (HH stage 25). Higher concentrations of vitamin A (2–4 μg/ml) inhibited membrane bone formation in all explants, and 4 μg/ml of vitamin A inhibited chondrogenesis in most (88%) of the older explants. To determine whether tissue interactions influence this effect of vitamin A on skeletogenesis, mandibular mesenchyme was separated from its epithelium and treated with vitamin A. Under normal culture conditions, isolated mesenchyme (HH stage 25) differentiated both cartilage and membrane bone. Hypervitaminosis A inhibited membrane bone formation in the isolated mesenchyme at all levels tested (1–4 μg/ml) and inhibited chondrogenesis at levels 2–4 μg/ml. Hence, vitamin A can act directly upon the mesenchyme to inhibit both membrane bone formation and chondrogenesis, but its action is mitigated by the presence of the epithelium.
Functional anatomy of the major cardiac nerves in cats
Authors: Phillips John G. , Randall Walter C. , Armour J. Andrew 
Published: February 2005

AbstractIn recognition of the extensive use of the cat as an experimental model of cardiac innervation, the effects of electrical stimulation of stellate ganglia, thoracic vagosympathetic complexes, and individual feline cardiopulmonary nerves on heart rate, blood pressure, and contractility in all four cardiac chambers were analysed and correlated with the anatomy of the thoracic autonomic nervous system. The right and left stellate ganglia in cats are relatively large and globular. Distinct dorsal and ventral ansae subclavia arise from these ganglia, connecting with the relatively small, spindle‐shaped middle cervical ganglia situated in the apices of the thoracic cage bilaterally. A cranial pole nerve arises from each of the middle cervical ganglia and courses cranially to unite with the ipsilateral superior cervical ganglia. On each side, the major cardiopulmonary nerves arise from the middle cervical ganglion, the relatively large vagosympathetic trunk, and the stellate ganglion. On the right side these nerves consist of a very small right stellate cardiac nerve, a recurrent cardiac nerve, a group of craniovagal nerves and a group of caudovagal cardiopulmonary nerves. On the left side are the left stellate cardiac, ventrolateral, ventromedial, and innominate cardiopulmonary nerves. All of these nerves contain efferent parasympathetic and/or sympathetic fibers which modify cardiac chronotropism and/or inotropism. Some contain afferent fibers. These results indicate that specific cardiopulmonary nerves exist in cats, which when stimulated, modify the cardiovascular system in specific fashions.
Localized vascular regression during limb morphogenesis in the chicken embryo: II. Morphological changes in the vasculature
Authors: Latker Carole H. , Feinberg Richard N. , Beebe David C. 
Published: February 2005

AbstractThe regression of blood vessels in the distal wing bud of chicken embryos from stages 19 to 31 was examined by light and electron microscopy. The vessels were double‐labelled by an injection of Monastral blue B (MB) to label the regressing endothelial cells, followed 6–48 hours later with an injection of India ink which marked the lumens of patent vessels. Prior to stage 26 the vessels contained only India ink since the endothelial cells were not phagocytic at this stage. Vessels at stage 26 or later were often double‐labelled, with MB sequestered in the endothelial cell cytoplasm and India ink in the vessel lumens. After stage 27 cells not associated with lumens, but labelled with MB, were observed in areas undergoing vascular regression. Ultrastructural changes in the endothelial cells as the vessels regressed included formation of luminal and abluminal processes, long complex junctions, and vacuoles containing MB. In many involuting vessels the endothelial cells appeared normal even though the lumens were collapsed. Occasionally, isolated pyknotic cells were observed in regions that had been previously vascularized. At stage 31 cells in the developing cartilage had vacuoles containing MB. Our study suggests that blood vessels may disappear from the prechondrogenic zone of the distal wing bud by several mechanisms. These could include a type of cell death that does not elicit a cellular infiltrate, migration of the endothelial cells away from vascularized regions, and/or transdifferentiation into cells that resembled chondrocytes.
Convergence of sensory processes from the heart and left ulnar nerve onto a single afferent perikaryon: A neuroanatomical study in the rat employing fluorescent tracers
Authors: McNeill Daniel L. , Burden Hubert W. 
Published: February 2005

AbstractAfter injection of true blue (TB) into the pericardial sac and nuclear yellow (NY) into the left ulnar nerve of rats, most perikarya in the left eighth cervical and first thoracic dorsal root ganglia are single‐labeled with either TB or NY. However, 7.1–14.7% of the sensory perikarya from the cardiac area labeled with TB are simultaneously labeled with NY. This finding indicates that some primary sensory perikarya receive processes from both the left arm and the heart. In addition to other mechanisms that may be operative in the referral of pain of cardiac origin to the medial left arm, these results suggest that sensory neurons with dichotomizing somatic and visceral peripheral processes may also contribute to this phenomenon.
Light and electron microscope demonstration of VIP‐ and enkephalin‐immunoreactive nerves in the human male genitourinary tract
Authors: Vaalasti Annikki , Tainio Hanna , Pelto‐Huikko Markku , Hervonen Antti 
Published: February 2005

AbstractVasoactive intestinal polypeptide (VIP) and enkephalins were demonstrated in the nerves of the human male urogenital tract by light and electron microscope immunohistochemical techniques. Nerves containing immunoreactivity to VIP were more numerous than enkephalin‐immunoreactive nerves. Both VIP‐and enkephalin‐immunoreactive nerves were detected in the vas deferens, prostate, seminal vesicles, and urinary bladder. In the kidney, testis, and epididymis no immunoreactive nerves could be demonstrated. By electron microscope both types of immunoreactivities were localized to the large granular vesicles of nerve terminals. VIP‐immunoreactive nerves were mostly found subepithelially, whereas enkephalin‐immunoreactive nerves were mainly related to smooth muscle cells. The possible functions of these peptide‐containing nerves are discussed.
A hypothesis on the allantoic origin of the distal midgut
Authors: Zarabi C. M. , Rupani Mahendra 
Published: February 2005

AbstractNo satisfactory explanation for the absence of the ileocecal portion of the digestive system in the newborns with cloacal exstrophy has been offered previously. This is a report of such a case in which the lymphocytes and plasma cells were used as tissue markers to identify the origin of the lymphatic‐rich ileocecal portion of the digestive tract. The absence of these cells, in this case demonstrated immunohistochemically, is suggestive of a dual origin of the midgut. Normal embryogenesis of the digestive system is reviewed and the possibility of participation of the allantois, in addition to the yolk sac, in the embryogenesis of the ileocecal segment of the gastrointestinal tract is discussed.
Freeze‐fracture analysis of intramembrane particles of erythrocytes from normal and dystrophic hamsters
Authors: Davis Elaine C. , Shivers Richard R. 
Published: February 2005

AbstractThe intramembrane particles on plasma membranes of erythrocytes of Syrian hamsters afflicted with hereditary muscular dystrophy were compared to those from normal controls by freeze‐fracture analysis. The reduced number of particles in both fracture faces of dystrophic erythrocyte plasmalemmae, as compared to that of control red cells, was found to be highly significant (P =.001). Results of this study therefore, support the concept of a generalized membrane defect (abnormality) in muscular dystrophy.
Pattern and distribution of intrahepatic lymph vessels in the rat
Authors: Niiro George K. , O'Morchoe Charles C. C. 
Published: February 2005

AbstractThe pattern and distribution of intrahepatic lymph vessels were examined by light and electron microscopy in rat livers fixed by perfusion through the portal vein. Lymph vessels were found in the connective tissue of the larger portal canals, where they coursed in close association with branches of the hepatic artery. The smallest portal canals contained no lymphatics. Of the portal canals that lacked a lymphatic, over 50% also lacked an arterial component. Direct connections between the lymphatic lumen and the spaces of Disse or Mall were not observed but lymphatics were found close to Mall's space, separated by only a sparse connective tissue space containing a few collagen fibrils. Lymphatics were neither seen within the parenchyma, nor associated with intercalated (sublobular) veins. Cross‐sectional area (223.2 ± 48.7 μm2 SEM), maximum diameter (20.5 ± 2.0 μm), volume density (0.00098 ± 0.00046 μm3/μm3) and profile density (1.8 ± 0.3 lymphatics per 1 mm2) of hepatic lymph vessels were determined by stereological measurement by a computer‐based image analyzer. These data were used to estimate the rate of lymph formation in the liver. It was concluded that (1) initial lymphatics probably originate in the portal canals; (2) the concept that fluid in the space of Disse can be regarded as the principal source of fluid‐forming hepatic lymph is questioned, since initial lymphatics appear to be separated from the space of Disse by hepatocytes and the space of Mall; and (3) the rate of lymph formation in the liver of the rat is approximately 0.06–0.08 μl/min/cm2 of lymphatic endothelium.
Differentiation and thyroid‐stimulating hormone (TSH) sensitivity of the fetal rat thyroid in organ culture
Authors: Yamamoto Masako , Takizawa Tatsuya , Arishima Kazuyoshi , Eguchi Yasunobu 
Published: February 2005

AbstractThyroids from rat fetuses of different ages (from day 14 to day 19 of gestation) were transplanted to organ culture for 2 days, with or without added thyroid‐stimulating hormone (TSH) in the medium. Thyroid tissue from 14‐day fetuses that initially consisted of irregularly arranged cell cords did not form follicles when cultured in the presence or absence of TSH. Thyroids from 15‐ and 16‐day fetuses initially consisted of epithelial cell masses. When cultured in the presence or absence of TSH they formed follicles, and a majority stored small amounts of colloid. In thyroid transplants from 17‐day fetuses, the response to TSH appeared as a significant increase in the follicular diameter and cell height. Thereafter, in all transplants cultured in the presence of TSH, both the follicular diameter and the cell height were markedly greater than in the transplants cultured in the absence of added TSH. These results suggest that the initial formation of thyroid follicles is independent of TSH and that, once developed, follicles become able to respond to TSH.
Influence of colchicine on the distribution of horseradish peroxidase in the secretory ameloblast layer in vitro
Authors: Matsuo Saburou , Yamamoto Katsuhiko , Nishikawa Shinji , Ichikawa Hiroyuki , Wakisaka Satoshi , Takano Yoshiro , Akai Michio 
Published: February 2005

AbstractThe distribution of exogenous horseradish peroxidase (HRP) in the secretory ameloblast layer of developing rat molar tooth germs was examined in a culture system with and without colchicine. The secretory ameloblast of cultured tooth germs engulfed HRP added to the medium regardless of the presence of colchicine. The reaction product was localized in various vesicles and granules. Without colchicine in the medium, many small vesicles containing HRP were located in the Tomes' processes, whereas only a few were present with colchicine at concentrations above 5 μM. An intense reaction of HRP also appeared in the distal extracellular spaces beyond the distal junctional complexes of ameloblasts cultured without colchicine, whereas it became almost indiscernible in the tooth germs cultured with colchicine. The lack of HRP in the Tomes' processes and distal extracellular spaces of ameloblasts treated with colchicine might be attributed to the disruption of microtubules. The present study suggests that the secretory ameloblast is able to transport tracer molecules through the intracellular pathway from the proximal and lateral extracellular spaces to the distal extracellular space.
Vascularization of the rat cornea after prolonged zinc deficiency
Authors: Leure‐Dupree Alphonse E. 
Published: February 2005

AbstractNeovascularization of the anterior stroma of the rat cornea was associated with prolonged zinc deficiency (in this model). There was also an increase in the myelinated nerves of the cornea. Blood vessels were not observed in the corneas of the pair‐fed and ad‐libitum‐fed control animals. The invading blood vessels were frequently associated with Schwann cells and neurites. Unmyelinated nerves were observed in the corneal stroma of all three experimental groups.
Sorting and transepithelial transport of adsorbed protein tracers: Effects of temperature
Authors: Wilson Jean M. , King Barry F. 
Published: February 2005

AbstractThe epithelium of the guinea pig yolk sac is involved in the selective transport of macromolecules to the fetus. We studied the compartments involved in sorting and transepithelial transport of protein tracers and the effect of lowered temperature (18°C) on these events. Explants of yolk sac were incubated with a mixture of cationized ferritin (CF) and horseradish peroxidase (HRP, Sigma type VI). At 4°C, both tracers were bound to the cell surface and binding of an HRP‐gold complex was shown to be inhibited by mannan. At 37°C and 18°C, both tracers were taken up into tubules and vesicles in the apical cytoplasm. Usually the tubules contained a mixure of tracers, but they often showed a polarized distribution with CF and HRP at opposite ends. The vesicles also contained mixtures of the tracers, but some contained only one. In addition, there were some irregularly shaped vacuoles composed of saccules that contained either a mixture, HRP alone, or CF alone. These results suggest that these adsorbed ligands are binding to unique microdomains of the endocytic complex. After 20 min at 37°C coated vesicles 100 nm in diameter were located in the apical cytoplasm and coated vesicles of the same size were located at the lateral cell membrane. Usually they contained only HRP or CF, although occasional mixtures were seen. At 18°C, HRP was transported across the cells in 100 nm vesicles. However, transport of CF was completely inhibited at the lower temperature. Although uptake at 18°C was slower than that at 37°C, experiments with 125I‐CF allowed comparison of time points at which equal uptake had occurred. These experiments demonstrated that inhibition of CF transport was not due to decreased amounts of internalized CF. These differences in transport of HRP and CF suggest that multiple compartments are involved in the sorting and transepithelial transport of protein, and at least one is perturbed by lower temperature.
The rete ovarii of cattle and deer communicates with the uterine tube
Authors: Odend'hal Stewart , Wenzel James Guthrie Wheeler , Player Emory Craig 
Published: February 2005

AbstractTextbooks in embryology, histology, and reproductive biology erroneously state that the mammalian rete ovarii consists of a tubular structure in the medulla of the ovary which is closed at both ends. In white‐tailed deer and cattle, the lumen of the rete ovarii opens directly into the infundibulum near its attachment to the ovary. This serendipitous discovery followed the serial sectioning of over 100 ovaries. Secretions through this tuboretial opening may affect reproductive processes. Obstructions could explain the development of cysts of clinical importance in both human and veterinary medicine. This rather obscure structure may have more significance than previously recognized.
Filamentary tubular inclusions in type II pneumocytes of the guinea pig
Authors: Manabe Toshiaki , Ikeda Hiromi 
Published: February 2005

AbstractThe type II pneumocytes of guinea pigs were studied with a transmission electron microscope. It was shown that 5–20% of type II cells contained filamentary tubular inclusions. No reports of similar structures in type II cells of any species have been found in the literature to date.These inclusions measured 90 nm in diameter, varying up to 3 μm in length, and were generally present in the basal and lateral portions of the cells with a close association to the lamellar bodies. They were usually straight but could be curved and tended to aggregate into parallel stacks. In cross‐sections, these filamentary tubular inclusions were surrounded by a thickened unit membrane and were composed of microfilaments arranged in circular fashion around a central core. In longitudinal sections, they consisted of rod‐like bodies with three lines of filaments.The possible function of the filamentary tubular inclusions is also discussed.
Immunoelectron microscope observations on secretion of human placental lactogen (hPL) in the human chorionic villi
Authors: Fujimoto Sunao , Hamasaki Kunshige , Ueda Hiroshi , Kagawa Hirohiko 
Published: February 2005

AbstractImmunoelectron microscope localization of human placental lactogen (hPL) was investigated in the chorionic villi from week 7 to full‐term gestation with the protein A–gold technique. With specific antiserum against hPL, immuno‐reactive gold particles were found to be preferentially located in Golgi‐derived, electron‐dense small granules of 80–180 nm in the syncytiotrophoblast. Our electron micrographs indicate that these small granules increase in number in the course of gestation and are released by exocytosis from the apical cell surface. The present study reveals that hPL is segregated from the Golgi apparatus, stored in the syncytiotrophoblast as secretory granules, and released into the maternal blood.
Significance of the increase in glucose 6‐phosphatase activity in skeletal muscle cells of the mouse by starvation
Authors: Hirose Kazuto , Watanabe Jun , Kanamura Shinsuke , Tokunaga Hirohiko , Ogawa Ryokei 
Published: February 2005

AbstractThe effects of starvation on glucose 6‐phosphatase (G6Pase; EC 3.1.3.9., D‐glucose 6‐phosphate phosphohydrolase) and glycogen phosphorylase (EC 2.4.1.1.) activities, and on glycogen content, were studied in skeletal muscles (m. rectus femoris) of mice. In the muscle cells from fed animals, the cytochemical reaction product for G6Pase activity was observed in moderate amounts in the terminal cisternae of sarcoplasmic reticulum and in small amounts in the nuclear envelope, and was rare or absent in the intermyofibrillar sarcoplasmic reticulum. After 4 days of starvation, however, the reaction product became abundant in all of the terminal cisternae, intermyofibrillar sarcoplasmic reticulum, and nuclear envelope. Biochemical G6Pase and glycogen phosphorylase a (active form) activities were higher in the muscles of starved mice than in those of fed animals. The glycogen content decreased markedly in the muscles of starved mice. The results suggest that the role of the increased G6Pase in skeletal muscle cells of starved mice is to release glucose into the blood by hydrolyzing glucose 6‐phosphate produced through the increased phosphorylase activity.
Disposition of the manchette and related events in the feline spermatid
Authors: Sickels Kathy I. , Heath Everett 
Published: February 2005

AbstractThe manchette is a transient microtubular organelle previously considered to “disappear” prior to formation of the definitive midpiece of the spermatozoon. Goodrowe and Heath (1984) have suggested, however, that in stallions the final disposition of the microtubules of the manchette is into the residual cytoplasm. In the present study, spermiogenesis was examined by transmission electron microscopy of testicular samples from eight cats. Feline spermatids also had a manchette of cylindrical shape, largely located in a cytoplasmic collar peripheral to the presumptive midpiece. The parallel microtubules of the manchette were interconnected by arms. Some of these arms were still present after rupture of the manchette cylinder and movement of the microtubules into the residual cytoplasm. On displacement of the manchette microtubules, mitochondria, spherical in shape and peripherally located, moved centrally to elongate and encircle the flagellum to form the definitive midpiece.
Morphometric analysis of the growth of the normal fetal guinea pig lung
Authors: Collins Margaret H. , Kleinerman Jerome , Moessinger Adrien C. , Collins Alexander H. , James L. Stanley , Blanc William A. 
Published: February 2005

AbstractThe structural development of the fetal guinea pig lung is described and quantified morphometrically in this report.At 35 days gestation the lung is in the pseudoglandular phase of growth, by 40 days it is in the canalicular phase, and at 50 days the saccular growth phase has begun. At term (67 days), the fetal guinea pig lung appears mature.From the beginning of the canalicular to the end of the saccular phases, the correlation coefficient between lung volume and gestational age is +.98, between internal surface area and gestational age is +.94 and between total number of saccules and gestational age is +.97. Internal surface area (ISA) correlates closely with lung volume (r = +.99) and the correlation coefficient between total number of saccules and lung volume is +.98. At term, lung volume is 4.22 ml. ISA is 0.5 M2, and total number of saccules is 253 million. Parenchymal growth is achieved by increases in both number and size of airspaces in the canalicular phase, primarily by increases in number during the early saccular phase and largely by increases in airspace size near term.The total length of parenchymal elastic tissue increases from 223 M at 45 days gestation to 5,253 M at term. Elastic tissue fibers first appear in the parenchyma of the fetal guinea pig lung during the canalicular phase, when the rate of saccule formation is high. The quantitative increase in elastic tissue correlates closely with the increase in the total number of saccules from day 45 to day 60 of gestation (r = +.99). The rate of elastic tissue growth increases sharply in the late saccular phase, coinciding with the period of greatest saccular expansion. These data suggest an interdependent relationship between saccular growth, i.e., proliferation and expansion, and the development of lung parenchymal elastic tissue.