bluuebunny/crossref_metadata_2025_split huggingface dataset:
Expression of collagen adhesion proteins and their association with the cytoskeleton in cardiac myocytes
Authors: Terracio Louis , Gullberg Donald , Rubin Kristofer , Craig Susan , Borg Thomas K. 
Published: February 2005

AbstractPrevious investigations have shown that specific cell surface glycoproteins on rat hepatocytes (COLL‐CAM) are involved in the recognition of interstital collagens (Rubin et al., Exp. Cell Res., 164:127–138, 1986). Western blot analysis with anti‐COLL‐CAM antibodies revealed the presence of a variable but restricted number (two) of glycoproteins in detergent‐extracted membranes from rat hearts at various developmental stages. Using antibodies against these collagen adhesion proteins, we show an expression of the antigens during different developmental stages of the rat heart and during cardiac hypertrophy. This expression is described morphologically by immunohistochemical staining of cell surfaces of freshly isolated myocytes from neonates, normal adults, and hypertrophied adult hearts. Antibodies made against COLL‐CAM were localized on the cell surface of cardiac myocytes and antibodies against talin and vinculin co‐localized in a similar position on the inside of the cell. Antibody staining appears to be increased at times when collagen synthesis is high (neonate and cardiac hypertrophy) and low when collagen synthesis is low, as in the normal adult. These results indicate that collagen adhesion proteins may play an important role in linking the extracellular matrix to the cytoskeleton in the heart.
Localization of fibronectin in megakaryocytes of fetal liver
Authors: Bockman Dale E. , Gulati Adarsh K. 
Published: February 2005

AbstractAntibodies specific for fibronectin were utilized to determine the sites of localization in the liver during development. The livers of fetal rats from each of gestation days 11‐19, and from days 1 and 8 postpartum, were studied by fluorescence microscopy. Fibronectin was localized predominatly in megakaryocytes and megakaryocyte precursors, and to a lesser extent in the extracellular matrix surrounding blood vessels and between hepatocytes and sinusoids. The cytoplasm of megakaryocytes and their precursors displayed bright fluorescence but their nuclei were negative for fibronectin. Hepatocytes had negative or faint fluorescence. Megakaryocytes were present in the liver from day 12, and were numerous from day 13 through most of the rest of gestation. The relative numbers of megakaryocytes decreased in later gestation; at 8 days postpartum only a few were observed per section. Hepatic megakaryocytes appeared before megakaryocytes were established in spleen and bone marrow. The early and persistent high levels of fibronectin in hepatic megakaryocytes, in the absence of comparable localization within hepatocytes, leads us to the hypothesis that megakaryocytes are important in establishing circulating fibronectin levels in the fetus. Similarly, bone marrow megakaryocytes may contribute to circulating fibronectin in the adult.
Tissue‐specific granularity of gap junction cytoplasmic surface revealed by rapid‐freeze, deep‐etch replicas
Authors: Shibata Yosaburo , Izumi Toshihiro , Yamamoto Torao 
Published: February 2005

AbstractPrevious rapid‐freeze, deep‐etch replica studies have revealed the differences between heart and liver gap junctions; cytoplasmic surfaces of in situ and phenylmethylsulfnoyl fluoride (PMSF)‐unproteolyzed isolated cardiac gap junctions (MW 47 kD) have a particulate substructure, which is absent both in the proteolyzed heart junctions (MW 29 kD) and in the liver junctions isolated with PMSF (MW 28 kD). The present deep‐etch replica studies of gap junction cytoplasmic surface (CS) membranes in several tissues of rats and mice were performed to examine whether or not this difference between liver and heart is typical of variations in gap junction proteins from tissue to tissue.In surface mucous cells of the stomach, intestinal epithelial cells, and kidney tubule cells, these epithelial gap junctions always showed smooth cytoplasmic surfaces, similar to the liver gap junctions. In contrast, in the atrial myocardium, aortic endothelium, and the ciliary process, cytoplasmic surface membranes of the gap junctions consistently revelaed particulate patterns. Close examinations disclosed that those granular structures were not merely attached to the membrane surface, but they also protruded from the membrane interior as an integral component of gap junctions particles. Furthermore, in the pregnant rat uterus at term, cytoplasmic surface membrances of myometrial smooth muscle gap junctions were particulate, but those of endometrial epithelium were smooth.The present observations strongly suggest that tissue specificity exists in cytoplasmic surface structures of gap junctions between the “true” epithelial and the noneepithelial tissues: the nonepithelial gap junctions contain the additional cytoplasmic surface domain that is absent in the gap junctions of “true” epithelial origin.
Cell proliferation in chick oral membrane lags behind that of adjacent epithelia at the time of rupture
Authors: Miller Sue Ann , Olcott Christopher W. 
Published: February 2005

AbstractRadioautographic analysis showed that ectoderm and endoderm cells in chick oral membrane continued to label with tritiated thymidine through the period of rupture, but their frequency of labeling was significantly lower than those of adjacent epithelia. Frequency of labeling increased in adjacent ectoderm and endoderm, while oral membrane rates remained relatively low, suggesting that growth in the membrane lags relative to adjacent epithelia. Relatively greater proliferation in adjacent epithelia could generate tension and pull apart the thinned oral membrane. Differentials in rates of cell proliferation, when considered along with knowledge of cellular rearrangements following changes in basal lamina and matrical components, suggest that differential growth is an important force in rupture of the avian oral membrane.
Immunocytochemical localization of hepatic fatty acid binding protien in the rat intestine: Effect of fasting
Authors: Iseki Shoichi , Hitomi Masahiro , Ono Teruo , Kondo Hisatake 
Published: February 2005

AbstractLocalization of hepatic fatty acid binding protein (h‐FABP) in the small and large intestines of rats was studied by light and electron microscopic histochemistry using the peroxidase‐antiperoxidase (PAP) method. In the small intestine of rats fed ad libitum, an intense FABP immunoreactivity was confined to the absorptive epithelial cells of the villi, but not of the crypts. The lowest margin of the immunoreactive cell sheet was closer to the crypts in the proximal than in the distal portions of the small intestine. In the large intestine, FABP immunoreactivity was present in the surface epithelial cells, with higher intesity in the proximal than in the distal portions of the intestine. After fasting rats for two days, many crypt cells exhibited intense immunoreactivity for h‐FABP, resulting in an extension of the lowest margin of the immunoreactive cell sheet deep into the crypts. Such expansion of the immunoreactive cell population was reversed by refeeding the animals. With regard to the intracellular localization of immunoreactivity in the jejunum, the basolateral portion of the cytoplasm exhibited a more intense immunoreaction than the apical portion in the majority of immunoreactive cells lining the villi, whether the animals were fed or fasted. The immunoreactive products appeared in the cytoplasmic matix without association with any subcellular structures. Although clusters of cells located in the villous tips exhibited evenly dense immunostaining throughout the entire cytoplasm, no increasing gradient in the intensity of the immunoreactivity from the base to the apex of the cytoplasm was seen in any epithelial cells. The present findings imply that h‐FABP could be involved in the uptake and metabolism of plasma‐derived as well as dietary‐free fatty acids by the intestinal epithelial cells.
S‐100 protein‐immunoreactive cells in the bovine ovary
Authors: Kamiya Shinji , Tsukushi Masumi , Yamano Shuji , Daigo Masayuki 
Published: February 2005

AbstractThe present study deals with an immunohistochemical localization of S‐100 protein in the bovine ovary. Immunoreactivity for S‐100 was observed in various types of cells, as well as in cells of the nervous system. The endothelial cells of arterial vessels, blood capillaries, and lymph vessels; the epithelial cells of ovarian cysts; and the oocytes of normal and atretic follicles showed an S‐100 protein positivity. The immunoreactivity also was found in the epithelial cells of the rete ovarii. No cells other than these showed immunoreactivity to the anti‐S‐100 serum. S‐100 protein can be a useful marker for providing information on ovarian function.
Effects of progesterone and a progesterone antagonist (RU486) on germinal vesicle breakdown in the mouse
Authors: Batten Bruce E. , Roh Sung I. , Kim Moon H. 
Published: February 2005

AbstractThe possibility that ovarian steroids may participate in the inhibition of meiosis has not been rigorously examined. Since progesterone levels are extremely high in follicular fluid prior to ovulation, we tested the possibility that this steroid may be involved in oocyte maturation. To this end, we collected follicular oocytes and cultured them in the presence of dibutyrl cAMP (Bt2), progesterone, and/or the progesterone antagonist RU486 and assessed maturation evidenced by germinal vesicle breakdown (GVBD). Denuded oocytes or cumulus masses collected in the presence of 1 mM Bt2 and subsequently cultured in 25 μM progesterone did not undergo GVBD. However, denuded oocytes and cumulus masses collected in the presence of progesterone and not Bt2 did undergo GVBD (93%). Concentrations of Bt2 (150 μM) that would not inhibit GVBD were inhibitory when used in the presence of progesterone (1–25 μM). Competition experiments using increasing concentrations of the progesterone antagonist RU486 (1–100 μ) did not block the ability of progesterone to enhance the activity of Bt2. We conclude that progesterone alone does not block GVBD; however, in the presence of low concentrations of cAMP it is extremely effective in blocking GVBD. The synergistic activity of progesterone does not appear to be mediated by the progesterone receptor. The data suggest that progesterone and cAMP may operate cooperatively to inhibit meiosis in the ovarian follicle.
Epidermis, basement membrane, and connective‐tissue healing after amputation of mouse digits: Implications for mammalian appendage regeneration
Authors: Neufeld Daniel A. 
Published: February 2005

AbstractSoft tissues from amputation sites of mice were examined at both light and electron microscope levels to determine whether features of growth buds (blastemas), which are necessary for amphibian limb regeneration, exist in nonregenerating mice. Several such features were found. A small area of the wound bed was covered by wound epithelium which, as in regenerating newt limbs, initially lacked an underlying basement membrane. Serially sectioned digits revealed blastemalike growth in the subdermal layer surrounding periosteal chondrogenic cells. Mesenchymelike cells were seen among the fibroblasts and leucocytes within the proliferating tissues. However, no evidence of dedifferentiation was seen in the dermis, which persisted as an apparent intact obstruction to growth bud formation. Existence of the essential ingredients of growth buds and soft‐tissue proliferation adjacent to chondrogenic cells proximally suggest that the tissues of mammalian healing may differ quantitatively rather than qualitatively from tissues of appendage regeneration. This premise is encouraging for efforts at growth enhancement in mammals.
Occurrence of calcitonin‐positive C cells within the distal vagal ganglion and the recurrent laryngeal nerve of the chicken
Authors: Kameda Yoko 
Published: February 2005

AbstractThe chicken ultimobranchial glands are richly supplied with nerve fibers originating from both the main trunk of the vagus nerve and its branch‐the recurrent laryngeal nerve. C cells immunoreactive for calcitonin were invariably found in the large nerve bundles distributed throughout the ultimobranchial glands. In addition, these cells were often present within the distal vagal ganglia and the recurrent laryngeal nerves. The frequency of occurrence and the pattern of distribution of the C cells in the distal vagal ganglia and the recurrent laryngeal nerves were determined in chickens of various ages by means of an immunoperoxidase method with anticalcitonin and antineurofilament antisera. The left and right sides of the ultimobranchial region were asymmetrical. The left ultimobranchial gland was in close contact with the vagus nerve trunk, especially with the distal vagal ganglion, but it was separated from the recurrent laryngeal nerve. The right gland contacted the recurrent laryngeal nerves, its medial edge being frequently penetrated by the nerve, but the gland was separated from the distal vagal ganglion. On the left side, C cells were found in 25 out of 39 distal vagal ganglia but they were not distributed in the recurrent laryngeal nerve. On the right side, the cells were present in 28 out of 43 recurrent laryngeal nerves but absent in the distal vagal ganglia. The results indicate that the C cells secreting a hormone calcitonin can enter into nerves, but their occurrence is restricted to the nerves in close proximity to the ultimobranchial glands. Electron microscopic studies revealed that C cells in the nerves received numerous axon clusters enveloped with Schwann cell cytoplasm. Naked axons regarded as axon terminals were found in direct contact with the surface of C cells. They were mainly composed of efferent‐type nerve endings showing the accumulation of numerous small clear vesicles and a few large dense‐cored vesicles. In addition, C cells were partly covered with the long cytoplasmic processes of Schwann cells and were also in contact with the Schwann cell perikarya. The C cells in nerves appear to be controlled by neural stimulation.
Osteocalcin‐hydroxyapatite interaction in the extracellular organic matrix of bone
Authors: Hauschka Peter V. , Wians Frank H. 
Published: February 2005

AbstractOsteocalcin, a major noncollagenous matrix protein of bone, dentin, and cementum, is found in tight association with the calcium phosphate mineral phase of these tissues. This article reviews the structural data for osteocalcin relevant to mineral adsorption. The equilibrium‐binding properties for Ca2+ ions and hydroxyapatite are considered, along with the apparent physicochemical effects of osteocalcin on bone mineral dynamics. Several of osteocalcin's possible biological activities (involvement in mineralization, chemoattraction, and leukocyte elastase inhibition) are discussed in relation to the mineral‐adsorption characteristics of this protein.
Mineral phases of calcium phosphate
Authors: Nancollas G. H. , Lore M. , Perez L. , Richardson C. , Zawacki S. J. 
Published: February 2005

AbstractMany studies of calcium phosphate precipitation have been made using relaxation techniques in which the concentrations of the lattice ions are allowed to decrease as equilibrium is approached. Since the nature of the phases that form depend markedly on the solution composition, this decrease can lead to concomitant phase transformations during the crystallization experiments. The results of the present constant composition (CC) studies show that defect apatites may be formed under conditions of sustained supersaturation with a non‐stoichiometric coefficient dependent on the pH of the growth medium. An important factor in analyzing these experiments is the initial surface modification and ion‐exchange processes involving H+ and Ca2+ ions after inoculation of the supersaturated solutions. Thereafter, active growth sites may be eliminated as the crystals undergo lattice perfection. Transformation of dicalcium phosphate dihydrate to octacalcium phosphate, involving dissolution and subsequent nucleation and growth of the new phase, is also influenced by surface roughening of the initial phase. Typical inhibitors that reduce the rate of growth of seed crystals in supersaturated solutions may actually induce the nucleation of calcium phosphate phases when immobilized on inert surfaces. This may be a factor in the modulation of crystal growth in many biological systems.
Morphometric analysis of the development of sexual dimorphism of the mouse pelvis
Authors: Iguchi Taisen , Irisawa Satoko , Fukazawa Yugo , Uesugi Yasuo , Takasugi Noboru 
Published: February 2005

AbstractSex differences in the innominate bone of C57BL/Tw mice were studied morphometrically from the day of birth to 120 days of age. In neonatal male and female mice, a small cartilaginous spine was found on the basal part of ischium. This process disappeard in males within 24 hours after birth, whereas in females it remained until at least 30 days. Other sexual differences in the pubis and the ischium appeared at 30 and 120 days, respectively. The pubis in female mice was longer and thinner than that in the males, and the ischium in male mice was shorter and thicker than that in the females. Thirty‐day‐old female mice treated neonatally with testosterone or 5α‐dihydrotestosterone possessed public bones shorter and thicker than those to the age‐matched untreated females. Pubes in male mice castrated at the day of birth were thinner than those in intact males. These findings suggest that the shape of the innominate bone is transformed to the male type under the influence of early postnatal androgen.
Intercellular communication between rat anterior pituitary cells
Authors: Soji Tsuyoshi , Herbert Damon C. 
Published: February 2005

AbstractCell‐to‐cell communication within the rat anterior pituitary was investigated in 60‐day‐old male rats with immunohistochemistry, scanning electron microscopy, freeze‐fracture electron microscopy, and conventional transmission electron microscopy. A dense cytoreticular network of cytoplasmic processes from the folliculostellate cells was found to contain immunoreactive S‐100 protein and was observed throughout the anterior pituitary. Nonimmunoreactive cells, which were granular, were situated in the center of each network. Almost all of the granulated cells were situated in close proximity to the folliculostellate cells. Scanning electron microscopy revealed that the gland consisted of microlobules enclosed by a basal lamina. On the surface of the microlobules were blood vessels whose branches invaded its internal structures. Cytoplasmic processes from folliculostellate cells projected outside the microlobule. Freeze‐fracture electron microscopy demonstrated the presence of numerous intramembranous particles on the P‐face of the plasma membrane. Scattered on the cell surface were groups of particles forming gap junctions. Meshworks of ridges which were representations of tight junctions were also observed near clusters of microvillous fragments. Clusters of particles forming small gap junctions were located between the meshworks of tight junctions. Small gap junctions were clearly observed by conventional electron microscopy between junctional complexes in a manner similar to that seen by freeze‐fracture electron microscopy. Slender cytoplasmic processes of folliculostellate cells came in contact near the basal lamina and were adjoined by small gap junctions. The ratio of nongranular cells which contained gap junctions to those in which the junctions were absent was about 1:1. The size of the gap junctions ranged from 50 nm to 3 μm. No gap junctions were observed along the plasma membranes of the granular cells. The significance of an intercellular communication system within the anterior pituitary gland of the rat is to establish a mechanism for rapid transmission of information in an organ which lacks direct innervation.
Ultrastructural study of the coiled body and a new inclusion, the “mykaryon”, in the nucleus of the adult rat sertoli cell
Authors: Schultz Michael C. 
Published: February 2005

AbstractRandom and serial thin sections of the nucleus in adult rat Sertoli cells were examined by electron microscopy. Besides the previously reported nucleoli and heterochromatin masses, the nuclei contain a coiled body and a new structure, the “mykaryon.”The coiled body is 835 nm in maximum diameter. It is composed of distinct elements referred to as “coils”. They are 32 nm wide on average and resemble the nucleolar pars fibrosa in their intense staining with heavy metal salts and their composition of narrow filaments. The coiled body is often close to a nucleolus, though no direct contact is established, and it sometimes exists at a distance from the nucleolus.The mykaryon is spherical, 460 nm in maximum diameter, and composed of a tridimensional network of 7–26 nm‐wide electron‐opaque “cords” separated by slighly thinner spaces. It has not been observed in the vicinity of a nucleolus. A literature survey showed no previous mention of a structure similar to the mykaryon. The coiled body and the mykaryon are interpreted as normal constituents of the Sertoli nucleus in the adult rat.
Musculotopic innervation of the primary flight muscles, the pectoralis (pars thoracicus) and supracoracoideus, of the pigeon (Columba livia): A WGA‐HRP study
Authors: Sokoloff A. , Deacon T. , Goslow G. E. 
Published: February 2005

AbstractThe distribution of motoneurons innervating the primary depressor and elevator muscles of the wing of the domestic pigeon (Columba livia) was studied by using the retrograde axonal tracer lectin‐conjugated horseradish peroxidase (WGA‐HRP). Injection of WGA‐HRP into the pectoralis (pars thoracicus) labeled neurons in the ventromedial corner of the lateral motor column of the spinal cord. These neurons were arranged in a column extending from spinal segment X or XI to spinal segment XII or XIII. The pectoralis, the primary depressor muscle of the wing, consists of two parts which are anatomically and functionally distinct, the sternobrachialis (SB) and thoracobrachialis (TB). Injection into the SB labeled neurons in the rostral and middle regions of the pectoralis motoneuron column. In contrast, injection into the TB labeled neurons in the middle and caudal regions of the pectoralis motoneuron column. Injection into the primary elevator muscle of the wing, the supracoracoideus, labeled neurons in the lateral motor column in spinal segments X and XI. These motoneurons were located dorsolateral to motoneurons labeled following pectoralis injection. These data demonstrate musculotopic segregation of the motoneurons innervating the primary flight muscles in the pigeon and, further, illustrate that the SB and TB subregions of the pectoralis are innervated by discrete aggregations of motoneurons.