bluuebunny/crossref_metadata_2025_split huggingface dataset:
Embryological development and prevalence of thumb flexion creases
Authors: Kimura Sumiko , Schaumann Blanka 
Published: February 2005

AbstractA study of the embryological development and morphology of the thumb flexion creases is presented. We used 178 human fetuses, at 6–20 weeks of gestational age, and 225 normal adults, aged 19–81 years, to observe the morphology and the timing and location of the appearance of the flexion creases. Most creases, that is, the regular, extra, and oblique creases, were found to develop concurrently with the appearance of the fetal volar pads, apparently independently of the thumb flexion movements. Although the regular creases usually appear to be simple, single creases, they seem to be formed by the radial and ulnar lateral crease segments that develop inwards from each lateral side. Our observations also suggest that the oblique and extra creases on the proximal phalanx of the thumb should be considered as common or “regular” creases, rather than anomalies, because of their high freqency in fetuses and in normal healthy adults.
Lifetime of the osteoblast in mouse periodontium
Authors: McCulloch C. A. G. , Heersche J. N. M. 
Published: February 2005

AbstractThe kinetics of osteoblasts and osteocytes on appositional and resorptive surfaces of mouse alveolar bone were examined using 3H‐thymidine and 3H‐proline radioautography. Our results show that the osteoblasts at the appositional surface of the the mouse periodontium are recruited from a progenitor population in the G1 phase of the cell cycle that goes through a single S‐phase before differentiating into osteoblasts and that the active lifetime of the osteoblasts on the periodontal surface is approximately 20 days. The lifetime of the osteoblasts on periosteal and endosteal surfaces is 10 days. The active lifetime of an osteoblast appears to be independent of the amount of matrix produced.
Architecture and structure of canine veins with special reference to confluences
Authors: Stone Elizabeth A. , Stewart Gwendolyn J. 
Published: February 2005

AbstractThe occurrence of cell‐infiltrated intimal lesions at the confluence of many small tributaries with canine jugular and femoral veins suggested that these areas (confluences) might (1) differ structurally from the rest of the receiving vein and (2) serve as initiation sites for thrombi. To explore these possibilities, the number of tributaries was determined by careful blunt dissection, and the architecture of confluences was studied by light and scanning and transmission electron microscopy. In addition to confluences formed by a named tributary (omobrachial), canine jugular veins averaged 11 confluences formed with small (0.2 to 2.5 mm diameter) unnamed tributaries that had not been previously described. Femoral veins averaged eight confluences of which four were formed with small unnamed tributaries. Double‐leafed valves were found at 90% of jugular and 76% of femoral vein confluences. Previously such valves were described only at the confluence of superficial with deep leg veins. Corrosion casts of iliac, saphenous, azygous, costocervical, and maxillary veins as well as cranial and caudal vena cava demonstrated a similar pattern of tributaries and valves.The three structures (receiving vein, tributary, valves) that formed the confluence differed, necessitating considerable modification as they approached the area of fusion. Jugular and femoral vein walls contained 5 to 10 layers of smooth muscle, abundant collagen, and a small amount of elastin. Tributary walls contained 0 to 2 discontinuous smooth muscle cell layers, limited collagen, and no elastin. As receiving veins approached a confluence, the thickness decreased by 15 to 77% except at valve attachment sites, which were thickened. A cluster of smooth muscle cells formed the junction of valve leaflets with vein. Endothelium was continuous over the luminal surface of all three structures. Calculations showed that these small‐valved tributaries make only a small contribution to venous return. On the other hand, there is considerable information to support the concept that local attenuation of the vein wall would lead to localized vessel dilation, resulting in rupture of the endothelium and basement membrane.
Development of the pulmonary vein in the american alligator (Alligator mississippiensis)
Authors: Kutsche Lynn M. , Van Mierop L. H. S. 
Published: February 2005

AbstractThe origin of the embryonic common pulmonary vein in terrestrial vertebrates is still uncertain. Most earlier studies in nonhuman embryos describe the vein as entering the sinus venosus. The currently prevailing view, however, based largely on the study of human material, is that the embryonic common pulmonary vein is associated with the left atrium from its inception.We recently observed the pulmonary vein entering the sinus venous part of the right atrium in several normal dog embryos of a stage comparable to horizon XIV in man (Streeter: Contrib. Embryol. Carnegie Inst. Wash., 31:53, 1945). In slightly older specimens the vein entered the left atrium just to the left of septum primum. This observation, and the fact that some atrial septal and pulmonary venous anomalies in man still await a plausible pathogenetic explanation, stimulated a restudy of the origin of the vein. The alligator was used because we already had prepared a large number of closely graded serially sectioned embryos for other purposes. Wax plate reconstructions clearly showed that the common pulmonary vein entered the left side of the sinus venosus. With the formation of the atrial septum, this part of the sinus venosus is “pinched off” and becomes incorporated into the left atrium, thus transferring the pulmonary venous ostium to that atrium.
Bone cell populations and histomorphometric correlates to function
Authors: Simmons D. J. , Menton D. N. , Russell J. E. , Smith R. , Walker W. V. 
Published: February 2005

AbstractA circadian context has been used to develop information about the proliferative and functional behavior of the cell populations that function to model the long bones of growing rats. We asked: Are the proliferating cells in the growth cartilages and diaphyseal bone of young adult growing rats distributed within single or multiple populations? Can cytomorphometry (TEM‐C) be used to determine ultrastructural correlates to the well‐defined circadian rhythm of matrix formation displayed by functionally synchronous populations of metaphyseal osteoblasts? Can TEM‐C reveal changes in osteoclast ultrastructure that could index a biological rhythm for osteoclastic bone mineralysis/resorption? Kinetic results derived from multiple radiothymidine labeling (DNA synthesis) support the single population model for chondrocytes and disphyseal osteoprogenitor cells. TEM‐C studies at the midpoints of the daily light and dark spans show that osteoblast RER‐membrane development and cysternal volumes are maximal at the recorded daytime peak of net collagen synthesis. The extent of metaphyseal osteoclast surface ruffling (mineralysis) is also twofold greater during the day than the night—an observation supporting the concept that bone formation and resorption activities are coupled.
Surface modifications at the periosseous region of chick osteoclast as revealed by freeze‐substitution
Authors: Akisaka Toshitaka , Subita Gus Permana , Shigenaga Yoshio 
Published: February 2005

AbstractImproved preservation of osteoclast fine structure can be achieved by quick freezing, freeze‐substitution, or detergent extraction. With such techniques the ruffled border mainly contains a disorganized, interconnected meshwork of microfilaments (5–7 nm in diameter), whereas in the clear zone a few ordered arrays of intermediate‐type filaments (10–12 nm in diameter) are detectable among the network of microfilaments. In well‐frozen samples, well‐preserved matrix may have occluded the cytoskeleton; detergent extraction permits visualization of the cytoskeletal components. In fresh‐frozen cells an extracellular fuzzy coat overlays the ruffled border. At the site of attachment of the clear zone to the bone surface, extracellular cementing material is detected only after quick freezing. The superiority of quick freezing to preserve ultrastructure is shown in various cytoplasmic organelles. Most vesicles and vecuoles found close to the ruffled border seemed not to make contact with the extracellular matrix. Anhydrous procedures using quick freezing and freezesubstitution stabilize bone mineral in some vacuoles and in the channels of the ruffled border.
Platelike and globelike inclusion bodies associated with rough endoplasmic reticulum in alveolar type 2 cells of the sheep
Authors: Shibamoto Toshishige , Kobayashi Toshio , Nagata Tetsuji 
Published: February 2005

AbstractWe studied the ultrastructure of alveolar type 2 cells of sheep. The inclusion bodies of rodlike structures or cisternal bodies derived from the endoplasmic reticulum were found in 13.6 ± 7.0% (± SD) of type 2 cells. The length of the Rod‐like structures were usually straight and arranged in parallel stacks. An electron‐dense line ran longitudinally at the center of the rodlike structures. Serial ultrathin sections revealed that the rodlike structures did not seem to be threedimensionally rod‐shaped structures but were actually plate‐disc or cup‐shaped, and the piled‐up rodlike structures were connected to each other at their ends. This rodlike structure in type 2 cells of sheep seems rather to be a platelike inclusion body. The cisternal body, on the other hand, was circular or oval‐shaped cisternae containing aggregated electron‐dense materials distributed in an arabesque or speckled pattern. Serial ultrathin section examination revealed the cisternal body to be three‐dimensionally a globe. Some plate bodies were arranged near the cisternal body, suggesting the transformation from the latter to the former. The functional significance of these findings has not yet been elucidated.
Distribution of fibronectins and laminin in the early pig embryo
Authors: Richoux Véronique , Darribère Thierry , Boucaut Jean‐Claude , Flèchon Jacques‐Edmond , Thiery Jean‐Paul 
Published: February 2005

AbstractFibronectins (FN) and laminin (LN) distributions were studied in the pig embryo by indirect immunofluorescence using antiporcine FN and antimurine LN antibodies.Extracellular FN are first detected in the early blastocyst before endodermal cell migration. They appear between the cells and on the blastocoelic face of the inner cell mass; thus, they are located at the interface of the trophectoderm and extraembryonic endoderm. Mesodermal cells migrate in a tridimensional network of fibrillar FN. These glycoproteins are also in the extraembryonic membranes (chorion and yolk sac wall) contiguous to the FN‐rich basement membranes of embryonic ectoderm and endoderm.Extracellular LN appears in the blastocyst when the endoderm is already established as a continuous cellular monolayer, and is located between the trophectoderm and the extraembryonic endoderm, which produces it. Laminin also accumulates at the basal surface of the embryonic ectoderm at the onset of gastrulation. In the extraembryonic membranes, LN appears at the interface of the endoderm and mesoderm and at the interface of the trophectoderm and mesoderm. It is produced and secreted by extraembryonic mesodermal cells.Analysis of the distribution of these glycoproteins suggests that FN allow the migration of endodermal and mesodermal cells by providing them with a suitable substrate. When these cells become immobilized, they synthesize LN, probably to stabilize their interactions with the underlying extracellular material and epithelia.
Perisynaptic satellite cells in human external intercostal muscle: A quantitative and qualitative study
Authors: Wokke J. H. J. , van Den Oord C. J. M. , Leppink G. J. , Jennekens F. G. I. 
Published: February 2005

AbstractIt is not known whether or not satellite cell nuclei are more common in the vicinity of motor endplates than in extrasynaptic regions of human muscle, as in animals. If so, perisynaptic satellite cells may have a role in preserving neuromuscular function. We compared the frequencies of satellite cell nuclei and of myonuclei in perisynaptic and extrasynaptic regions of human external intercostal muscle, and found an absolute as well as a relative increase of perisynaptic satellite cells. The mean frequency of satellite cell nuclei per sarcomere was 0.016 in perisynaptic and 0.00003 in extrasynaptic regions. The mean frequency of myonuclei per sarcomere was 0.098 in perisynaptic and 0.014 in extrasynaptic regions. We could not demonstrate any influence of aging on satellite cell distribution. Perisynaptic satellite cells had many processes, and some features suggested a more active state. These cells might add to the pool of junctional myonuclei for synthesis of acetylcholine‐receptor molecules or help in the repair of the postsynaptic membrane. Alternatively, they may synthesize basal lamina substances that are specific for the endplate.
Glycoconjugates in normal wound tissue matrices during the initiation phase of limb regeneration in adult Ambystoma
Authors: Young Henry E. , Dalley Bernell K. , Markwald Roger R. 
Published: February 2005

AbstractThe present study identifies localizes, and reports the relative composition of specific glycosaminoglycans within tissue matrices during the initiation phase of limb regeneration. The regenerate tissues were harvested and assayed morphologically, histochemically, and chemically. We observe 1) a population of cells interspersed among the cells of the dermis, epimysium, perimysium, perichondrium, and periosteum. 2) This population was distinguishable by a unique pattern of glycoproteins and extracellularly associated hyaluronate and glycoproteins. 3) Cells with these staining characteristics aggregated to a position directly beneath the apical epicermal cap. 4) Extracellular hyaluronate and glycoproteins colocalized with undifferentiated tissues. And 5) extracellular chondroitin sulfate, dermatan sulfate, and keratan sulfate glycosaminoglycans colocalized with differentiated tisues. The correlations of distinct glycoconjugate compositions with specific regeneration morphologies suggest the possibility that these components may be related to the phenotypic expression of tissues during regeneration.
Progesterone promotes a massive infiltration of the rat uterine cervix by the eosinophilic polymorphonuclear leukocytes
Authors: Luque Enrique H. , Montes Gregorio S. 
Published: February 2005

AbstractRat uterine cervices contained an eosinophilic infiltrate during labor, whereas samples of cervices obtained from nonpregnant controls had no infiltrate. A heavy eosinophilic invasion, which closely resembled that of the cervix uteri at term, could be reproduced in ovariectomized rats following progesterone administration, but not in spayed rats injected with estrogen. Light and electron microscopic evidence showing a widespread collagenolysis in the cervical stroma at term is presented. This collagenolysis follows the eosinophilic invasion. On the basis of these observations, a possible role for the eosinophilic infiltrate of the uterine cervix is discussed.
Primary cell culture and morphological characterization of ventricular myocytes from the adult newt, notophthalmus viridescens
Authors: Tate John M. , Oberpriller John O. 
Published: February 2005

AbstractPrevious work has demonstrated that adult newt cardiac myocytes possess a proliferative ability in response to an experimentally induced in jury, in vivo. This study describes an in vitro model in which the proliferative events of the adult cardiac myoctye may be studied. Ventricles were minced and then enzymatically dissociated in a Ca++‐ and MG++‐free salt solution containing 0.5% trypsin and 625 U/ml of CLS II collagenase for 8 to 10 hours at 25°C. Enzyme digests were preplated and then cultured on bovine corneal endothelial‐derived basement membrane “carpets” in either serum‐free or serumsupplemented modified Leibovitz's medium for up to 30 days. Light and transmission electron microscopic characterization demonstrated that a majority of the myocytes underwent an initial period of disorganization characterized by a “rounding up” of the cell and a loss of myofibrillar organization. Once the myocytes had attached to the culture substratum they began to spread out, underwent a reassembly of their contractile elements, resumed spontaneous contractions, and demonstrated ultrastructural evidence of protein synthesis. Mitosis was observed in several myocytes 8 to 15 days following isolation. In 15‐day serum‐supplemented and serum‐free cultures, 6.5% ± 0.9% and 8.1% ± 1.4% of the myocytes were binucleated, respectively. These results demonstrate that adult newt ventricular myocytes can be successfully placed into primary culture and are capable of undergoing mitosis. This work may be considered as a foundation for future investigations which will focus on the mechanisms which control cardiac myocyte proliferation.
Synthesis and secretion of collagen by cells of connective tissue, bone, and dentin
Authors: Leblond C. P. 
Published: February 2005

AbstractThe production of type I collagen by fibroblasts, odontoblasts, and osteoblasts is reviewed on the basis of results obtained by electron microscopy, 3H‐proline radioautography, and immunostaining for type I procollagen.In the three cell types, the percursors of type I collagen are processed along the rough endocplasmic reticulum (rER)‐Golgic‐secretory granule pathway in the same manner as secretory proteins, but the available evidence suggests a few special features: (1) From the rER site of synthesis, the initial collagen procursors, known as pro‐alpha chains, are transported to the Golgi apparatus within tubular structures, referred to as intermediate tubules, rather than within vesicles. (2) The pro‐alpha chains coil into a triple helix within spherical distensions present along the saccules on the cis side of Golgi stacks. (3) The resulting procollagens are fairly raigid and form bundles that cause spherical distensions to lengthen into cylindrical ones, whereas by an unknown mechanism these distensions become part of the saccules on the trans‐side of Golgi stacks. (4) The procollagen‐containing cylindrical distensions are resleased from trans‐saccules to become secretory granules, and some procollagen material finds its way into lysosomes. (5) The secretory granules release their procollagen content by exocytosis at the cell surface. (6) The released procollagen is transformed into collagen before or, more probably, after associating with the surface of a collagen fibril.
Role of lipids in calcification of cartilage
Authors: Boyan Barbara D. , Schwartz Zvi , Swain Larry D. , Khare Aruna 
Published: February 2005

AbstractThis review addresses the role of lipids and membranes in biologic calcification and examines their regulation during endochondral ossification. The close association of lipids with mineral deposition has been well established. Early observations indicated that lipids, particularly phospholipids, can not be totally extracted from calcified tissues until the tissues are decalcified. Phospholipids associated with mineral are also enriched in extracellular membrane vesicles, called matrix vesicles. Numerous studies indicate that mineral deposits in calcifying cartilage are first seen in these phosphatidylserine and alkaline phosphatase enriched vesicles and that the process of endochondral calcification of epiphyseal growth plate is possibly mediated by them. Matrix vesicles, and the phospholipids present in them, appear to be involved in initial formation of calcium hydroxyapatite crystals via the interaction of calcium and phosphate ions with phosphatidylserine to form phospholipid:Ca:Pi complexes (CPLX). CPLX is present in tissues which are undergoing initial mineral deposition but are absent from nonmineralizing tissues. Evidence suggests that CPLX resides in the interior of matrix vesicles where the earliest mineral crystals are formed in association with the vesicle membrane. More recently, it has been determined that specific membrane proteins, called proteolipids, participate in CPLX formation and hydroxyapatite deposition, in part by structuring phosphatidylserine in an appropriate conformation. Phosphatidylserine involvement in the initiation of mineralization has been extensively investigated because of its extremely high binding affinity for Ca2+. In addition to structuring a specific phospholipid environment, proteolipids may also act as ionophores, promoting export of protons and import of calcium and phosphate, both requirements of biologic calcification. In cartilage, enzyme activity, phospholipid and CPLX content and composition, and ability of proteolipids to support in vitro hydroxyapatite formation, are all part of the initial calcification cascade and are regulated by metabolites of vitamin D.
Organization of crystals in enamel
Authors: Warshawsky H. 
Published: February 2005

AbstractIt has been variously suggested that the organic matrix associated with the mineral phase of enamel is present as either calcified fibrils, central dark lines, peripheral sheaths around hexagonal crystals, or organic ghosts apparently contained within crystal profiles. The most consistent findings confirm the crystal ghost conception. Grid decalcification of nearly mature sectioned enamel and staining revealed hollow, noncrystalline structures whose external measurements were statistically identical to those of the dissolved crystallites, but with internal measurements too small to accommodate the crystallites. To explain these apparent ghosts in view of the incompatibility of ghosts with crystal structure, it has been proposed that the crystallites are not hexagonal in cross‐sections and the hexagonal appearance is due to projections of parallelepiped‐shaped crystallite segments with cut surfaces that are rhombiodal in shape. Material on the surface of such profiles would project as if it were contained within the profile. Hexagonal forms could not be demonstrated in isolated crystallites examined by transmission electron microscopy, high‐resolution scanning electron microscopy, and replicas made of the isolated crystallite preparations examined by transmission electron microscopy. Existing evidence does not rule out the possibility that the noncrystalline profiles represent stain drawn into the holes left by the dissolved crystallites as a result of high capillarity forces.
Morphometric analysis of bone marrow sinus cell elements after induction of monomyelocytic leukemia in BALB/c mice
Authors: Leonardi Gary Paul , Manthos Michael , Orlic Donald , Lobue Joseph 
Published: February 2005

AbstractMorphometric measurements of bone marrow sinus wall adventitial and endothelial cells were made in normal and leukemic samples by using a Bioquant II computer image analysis program (R & M Biometrics, Nashville TN). Electron micrographs of bone marrow from at least eight mice per group were studied in normal and day‐2, day‐4, and day‐6 leukemic postinoculation groups. The adventitial cells abuting the sinus endothelium was found to be significantly reduced with disease progression. In addition, adventitial cell area and perimeter were found to be drastically reduced with disease progression whereas endothelial cell area and perimeter showed no significant differences. Other investigators have suggested that the marrow sinus adventitial cell cover is drastically reduced in rodent leukemias (Chen et al.; Blood, 39:99–112, 1972; Campbell; Am. J. Anat., 142:319–334, 1975). Our findings give quantitative data to support this hypothesis.