bluuebunny/crossref_metadata_2025_split huggingface dataset:
A test of positional properties of avian wing‐bud mesoderm
Authors: Carlson Bruce M. 
Published: February 2005

AbstractSupernumerary wing structures are readily produced by grafting pieces of wing‐bud mesoderm into different locations of host wing buds, but the mechanism underlying their formation remains obscure. The major aim of this study was to examine the ability of posterior quail wing‐bud mesoderm, cultured in vitro long enough to lose ZPA (zone of polarizing activity) activity, to stimulate or participate in the formation of supernumerary structures when grafted into anterior slits of host chick wing buds. Small pieces of anterior and posterior quail wing‐bud mesoderm (HH stages 21‐23) were placed in in vitro culture for up to 3 days. After 2 days, ZPA activity of cultured mesoderm was lost. After the grafting of 2‐ to 3‐day cultured anterior quail wing‐bud mesoderm into posterior slits of host chick wing‐buds, a consistently high percentage (70%‐90%) of grafts result in formation of supernumerary cartilage; in this experiment, however, only a low percentage of grafts resulted in supernumerary cartilage when 2‐ to 3‐day cultured posterior mesoderm was grafted into anterior slits. Taken with controls, these results show that positional differences exist between cultured anterior and posterior wing‐bud mesoderm. Serial‐section analysis of numerous operated wings has shown several patterns of contribution to supernumerary structures by cells of graft and host. Single supernumerary digits induced by grafts of ZPA mesoderm into anterior slits were normally composed entirely of host cells, but graft cells regularly contributed to skeletal elements of more complex supernumerary structures. Cartilage rods produced by anterior‐to‐posterior grafts were composed mostly of graft cells, but cartilage nodules and the bases of some rods were often mosaics of chick and quail cells. The results support the proposition that mesodermal cells of the quail wing‐bud possess a form of anteroposterior positional memory, but its nature and the means by which the memory of grafted cells interacts with host mesoderm are still not clear.
Morphogenesis of the respiratory bronchiole in rhesus monkey lungs
Authors: Tyler Nancy K. , Hyde Dallas M. , Hendrickx Andrew G. , Plopper Charles G. 
Published: February 2005

AbstractThe epithelium of the respiratory bronchiole in the adult rhesus monkey consists of two populations: a pseudostratified epithelium with basal, mucous goblet, and ciliated cells located near the pulmonary artery (PA); and a simple cuboidal epithelium composed only of nonciliated bronchiolar epithelial (or Clara) cells in areas away from the PA. This study describes the pattern of differentiation of these two epithelial populations, and their relationship to the PA and to the time of appearance of alveoli. in the respiratory bronchiole of the rhesus monkey during the period of 90‐125 days gestational age (DGA). These events were related to changes in the adjacent parenchyma. Dissected airways of infusion‐fixed, critical‐point‐dried lungs were evaluated by scanning microscopy followed by light microscopy of the same airways. At 54% of gestation (90 DGA), the distal airway was lined by a mixture of ciliated and nonciliated cells. By 67% of gestation (110 DGA), the ciliated cells were confined to the epithelium over the PA. The underlying connective tissue initially was cellular containing few fibers but was fibrous by 76% of gestation (125 DGA). Alveolarization began near the most distal cartilage at 57% of gestation (95 DGA), the same period at which secondary septation occurred in the distal acinus. Thus, alveolarization occurred simultaneously in two centers: (1) the proximal centriacinar region in the vicinity of the most distal cartilage and (2) the distal lung parenchyma. The duration of centriacinar alvcolarization was short, approximately 5 days.
Ultrastructure of the osteogenesis of acellular vertebral bone in the Japanese medaka, Oryzias latipes (teleostei, cyprinidontidae)
Authors: Ekanayake Sunetra , Hall Brian K. 
Published: February 2005

AbstractAn ultrastructural study by transmission electron microscopy (TEM) of the vertebrae of embryonic, larval, juvenile and mature medaka shows that each vertebra consists of a core of notochordal cells surrounded by a sheath of bone. The vertebral bone lacks either fully or partially embedded cells in the matrix throughout development. Bone matrix is secreted by a layer of cells that lies over the outer surface of the vertebral bone. During the early stages of osteogenesis, these cells secrete bone matrix all around themselves. However, because of the gradual flow of the newly synthesized bone matrix through intercellular spaces, matrix‐producing cells do not become trapped in their own secretion. In later stages of osteogenesis, these cells secrete matrix only toward the already‐deposited bone. This polarized matrix secretion allows the osteoblasts to stay always on the bone surface and never to become trapped in the matrix as osteocytes.
Ultrastructure of the mineralizing metacarpophalangeal joint of progressive ankylosis (ank/ank) mice
Authors: Sampson H. Wayne 
Published: February 2005

AbstractThe metacarpophalangeal joint of the progressive ankylosis mouse was examined at 4, 6 and 8 weeks of age by using electron microscopy and electron probe microanalysis. These studies describe the progression of the disorder, and they reveal three overlapping phases: pannus proliferation, chondrophyte formation and mineralization, and articular cartilage mineralization. The chondrophyte mineralized in a manner fairly similar to endochondrial bone, whereas articular cartilage mineralized by advancement of a calcification front across the cartilage. Synovial crystal phagocytosis was also observed. The progressive ankylosis mouse should be an important model for studying both crystal deposition and abnormal articular cartilage calcification.
Structural manifestations of diabetic cardiomyopathy in the rat and its reversal by insulin treatment
Authors: Thompson Ed W. 
Published: February 2005

AbstractThe structural effects of diabetes and subsequent insulin treatment upon the contractile and supporting elements of the rat myocardium were examined at progressive stages of both untreated and treated disease. Diabetes was induced by intravenous injection of alloxan, and tissue was examined after 6, 12, and 26 weeks. Insulin treatment began after 12 weeks of diabetes and tissue from these animals was examined after the same intervals. Within the cardiocytes, diabetes produced a focal yet progressive loss of myofibrils, transverse tubules, and sarcoplasmic reticulum, and separation of the fasciae adherens was evident at the intercalated disk. Mitochondrial damage was not evident. These cytoplasmic alterations were accompanied by intercellular and perivascular deposition of connective tissue, thickening of the endothelial cytoplasm with pinocytotic hyperactivity, and characteristic basal laminar changes. When insulin treatment began after 12 weeks of diabetes, most, but not all, of these changes were reversed, and this reversal was essentially complete within 6‐12 weeks. Even with longer periods of insulin treatment, cardiocytes still exhibited scattered areas of myofibril loss and extracellular matrix was retained. In contrast, diabetic changes in the intercalated disk and capillaries, including their basal laminae, were completely and rapidly reversed. It is hypothesized that the structural manifestations of diabetic cardiomyopathy consist of two major components; the first is a short‐term, physiologic adaptation to metabolic alterations, while the other represents degenerative changes for which the myocardium has only a limited capacity for repair.
Computer ranking of the sequence of appearance of 40 features of the brain and related structures in staged human embryos during the seventh week of development
Authors: O'Rahilly Ronan , Müller Fabiola , Hutchins Grover M. , Moore G. William 
Published: February 2005

AbstractThe sequence of events in the development of the brain in human embryos, already published for stages 8‐17, is here continued for stages 18 and 19. With the aid of a computerized bubble‐sort algorithm, 58 individual embryos were ranked in ascending order of the features present. The increasing structural complexity provided 40 new features in these two stages. The chief characteristics of stage 18 (approximately 44 postovulatory days) are rapidly growing basal nuclei; appearance of the extraventricular bulge of the cerebellum (flocculus), of the superior cerebellar peduncle, and of follicles in the epiphysis cerebri: and the presence of vomeronasal organ and ganglion, of the bucconasal membrane, and of isolated semicircular ducts. The main features of stage 19 (approximately 48 days) are the cochlear nuclei, the ganglion of the nervus terminalis, nuclei of the prosencephalic septum, the appearance of the subcommissural organ, the presence of villi in the choroid plexuses of the fourth and lateral ventricles, and the stria medullaris thalami.
Immunohistochemical renin study of DES‐induced renal tumor in the Syrian hamster
Authors: Dodge Alice H. , Brownfield Mark , Reid Ian A. , Inagami Tadashi 
Published: February 2005

AbstractDiethylstilbestrol (DES) treatment of a male Syrian hamster resulted in the development of a renal tumor and its widely scattered scrosal metastases. Cells in both the primary tumor and metastatic nodules contained secretory granules. The tumors were transplanted serially into DES‐supported and non‐DES‐supported host hamsters until DES‐independent tumors developed. Rabbit antiserum to mouse salivary renin and rabbit antiserum to rat kidney resin were reacted with sections of the primary tumor, metastatic nodules, and all transport tumors. The sections were stained by the PAP and Vector‐ABC‐AP procedures. Renin‐positive material was observed in all tumors. Plasma renin activity (PRA) was determined for the host hamsters carrying the renal tumor transplants and compared to the PRA values that had been determined for normal non‐DES‐treated male and female hamsters. It was found that the average PRA values of host hamsters carrying the tumor transplants were significantly higher than the normal PRA ralues.
Innervation of the C cells of chicken ultimobranchial glands studied by immunohistochemistry, fluorescence microscopy, and electron microscopy
Authors: Kameda Yoko , Okamoto Kiyoshi , Ito Miyoshi , Tagawa Takasuke 
Published: February 2005

AbstractInnervation of the ultimobranchial glands in the chicken was investigated by immunohistochemistry, fluorescence microscopy and electron microscopy. The nerve fibers distributed in ultimobranchial glands were clearly visualized by immunoperoxidase staining with antiserum to neurofilament triplet proteins (200K‐, 150K‐ and 68K‐dalton) extracted from chicken peripheral nerves. The ultimobranchial glands received numerous nerve fibers originating from both the recurrent laryngeal nerves and direct vagal branches. The left and right sides of the ultimobranchial region were asymmetrical. The left ultimobranchial gland had intimate contact with the vagus nerve trunk, especially with the distal vagal ganglion, but was somewhat separated from the recurrent nerve. The right gland touched the recurrent nerve, the medial edge being frequently penetrated by the nerve, but the gland was separated from the vagal trunk. The left gland was innervated mainly by the branches from the distal vagal ganglion, whereas the right gland received mostly the branches from the recurrent nerve. The carotid body was located cranially near to the ultimobranchial gland. Large nerve bundles in the ultimobranchial gland ran toward and entered into the carotid body.By fluorescence microscopy, nerve fibers in ultimobranchial glands were observed associated with blood vessels. Only a few fluorescent nerve fibers were present in close proximity to C cell groups; the C cells of ultimobranchial glands may receive very few adrenergic sympathetic fibers.By electron microscopy, numerous axons ensheathed with Schwann cell cytoplasm were in close contact with the surfaces of C cells. In addition, naked axons regarded as axon terminals or “en passant” synapses came into direct contact with C cells. The morphology of these axon terminals and synaptic endings suggest that ultimobranchial C cells of chickens are supplied mainly with cholinergic efferent type fibers. In the region where large nerve bundles and complex ramifications of nerve fibers were present, Schwann cell perikarya investing the axons were closely juxtaposed with C cells; long cytoplasmic processes of Schwann cells encompassed large portions of the cell surface. All of these features suggest that C‐cell activity, i.e., secretion of hormones and catecholamines, may be regulated by nerve stimu1i.
Growth allometry of craniomandibular muscles, tendons, and bones in the laboratory rat (Rattus norvegicus): Relationships to oromotor maturation and biomechanics of feeding
Authors: Huhov Jack , Henry‐Ward Winsome , Phillips Lisa , German Rebecca 
Published: February 2005

AbstractThis study addressed the problem of how growth of Craniomandibular muscles, tendons, and bones influences the acquisition of oromotor skills and biomechanics of feeding in the laboratory rat (Rattus norvegicus). Rats representing a 6.6‐fold size range were dissected, and muscles, tendons, and mandibles were weighed. Cross‐sectional areas of tendons and bones providing attachment surfaces for muscles were estimated. Ontogenetie scaling of Craniomandibular muscles, tendons, and bones was described by using linear regression models, and departures from size‐required compensations were used to characterize changes in oromotor function. A two‐dimensional model was developed which permitted calculation of mechanical advantages of four masticatory muscles; the model was used to show how mandibular growth and tooth eruption influence the biomechanics of rat feeding. Relative to mandible weight, most jaw muscles scaled either isometrically or positively, tendon cross‐sectional areas scaled isometrically or negatively, and bone surfaces scaled negatively. With the exception of the superficial masseter and internal pterygoid muscles, mechanical advantages did not change significantly during mandible growth. Growth patterns of Craniomandibular muscles, tendons, and bones contribute significantly to changes in morphology and oromotor function.
Visualization of chromosome assembly during the S and G2 stages of the cycle and chromosome disassembly during the G1 stage in semithin sections of mouse duodenal crypt cells and other cells
Authors: El‐Alfy M. , Leblond C. P. 
Published: February 2005

AbstractPrevious examination of dividing cells in the isthmus of the mouse pyloric antrum by using semithin (0.5‐μm‐thick) Epon sections revealed that the prophasic condensation of chromosomes began early in the DNA‐synthesizing (S) stage. In order to examine whether the same observation could be made in other proliferating cell types, the crypt base columnar ceils in mouse duodenum and the hepatocytes of the rat 48 hr after partial hepatectomy were investigated by morphologic and radioautographic techniques.When crypt base columnar cells were studied in semi‐thin Epon sections, the four phases of mitosis showed the characteristic features described by classical cytologists. Moreover, the proportion of cells in prophase and telophase was high. To relate the mitotic phases to the stages of the cell cycle, the “frequency of labeled mitoses method” provided the duration of the cell cycle, 12.3 hr, and of the S stage, 7.3 hr. From the frequency of the occurrence of mitotic phases, it was estimated that metaphase lasted 0.3 hr and anaphase 0.11 hr, in line with previous estimates. However, the durations of prophase and telophase were long, 5.9 and 1.9 hr, respectively. The whole mitotic process took over 8 hr. From the duration of prophase and cycle stages, it was calculated that 67% of the S stage was occupied by prophasic cells. In fair agreement with this estimate, 68% of the labeled cells 10 min after a 3H‐thymidine injection were found to be in prophase.In regenerating hepatocytes, the morphological features and frequency of prophase and telophase cells were similar to those observed in duodenal crypt cells. While the cycle time was not measured and, therefore, the duration of cycle stages and mitotic phases could not be estimated, it is likely that their duration would be of the same order of magnitude.In conclusion, the mitotic process in duodenal crypt cells takes over 8 hr. Moreover, the crypt cells, like antral isthmal cells, show features of early prophase soon after they enter the S stage of the cycle.
Cyclic modulation of sertoli cell junctional complexes in a seasonal breeder: The mink (Mustela vison)
Authors: Pelletier R.‐Marc 
Published: February 2005

AbstractThe development and modulation of Sertoli cell junctions was studied in newborn and adult mink during the active and inactive spermatogenic phases. The techniques used were electron microscopy of freeze‐fractured replicas and thin sections of tissues infused with horseradish peroxidase as a junction permeability tracer. In the newborn, freeze‐fractured developing junctions had either spherical or fibrillar particles. In addition, Junctional domains where particles were associated preferentially with the E‐face, and others where particles were associated preferentially with the P‐face, were found developing either singly or conjointly within a given membrane segment, thus yielding a heterogeneous Junctional segment. Coincidently with the development of a tubular lumen and the establishment of a competent blood‐testis barrier, Junctional strands were composed primarily of particulate elements associated preferentially with the E‐face. In adult mink during active spermatogenesis, cell junctions were found on the entire lateral Sertoli cell plasma membrane from the basal to the luminal pole of the cell. In the basal third of the Sertoli cell, membranous segments that faced a spermatogonium or a migrating spermatocyte displayed forming tight, gap, and adherens junctions. In the middle third, abutting membrane segments localized above germ cells were involved in continuous zonules and in adherens junctions. In the apical or luminal third, the zonules were discontinuous, and the association of Junctional particles with the E‐face furrow was lost. Gap junctions increased in both size and numbers. Junctional vesicles that appeared as annular gap and tight‐junction profiles in thin sections or as hemispheres in freeze‐fracture replicas were present. Reflexive tight and gap junctions were formed through the interaction of plasma membrane segments of the same Sertoli cell. Internalized Junctional vesicles were also present in mature spermatids. During the inactive spermatogenic phase, cell junctions were localized principally in the basal third of the Sertoli cell; Junctional strands resembled those of the newborn mink. During the active spermatogenic phase, continuous zonules were competent in blocking passage of the protein tracer. During the inactive phase the blood‐testis barrier was incompetent in blocking entry of the tracer into the seminiferous epithelium. It is proposed that modulation of the Sertoli cell zonules being formed at the base and dismantled at the apex of the seminiferous epithelium follows the direction of germ cell migration and opposes the apicobasal direction of junction formation reported for most epithelia. The arrest of spermatogenesis coincides with dramatic changes in the dynamic modifications of Sertoli cell zonules.
Synthesis of lens capsule and plasma membrane glycoproteins by lens epithelial cells and fibers in the rat
Authors: Haddad A. , Bennett G. 
Published: February 2005

AbstractThe lens of the eye possesses a capsule which is a greatly hypertrophied basement membrane. To investigate the synthesis of glycoproteins destined for this capsule, 3H‐fucose was iryected into the vitreous body of intact rats weighing approximately 200 gm. The animals were killed from 10 min to 14.5 months later, and their lenses were processed for electron microscope radioautography. At 10 min after injection, more than 58% of the silver grains were localized to the Golgi apparatus of the lens epithelial cells. By day 1, the heaviest sites of reaction were the plasma membrane (more than 50% of total label), the basal cytoplasm, and the adjacent lens capsule, where a heavy band of reaction was seen. The remainder of the capsule exhibited a lighter diffuse reaction. In the lens fibers, the label was at first localized to clusters of vesicles but then migrated to the plasma membrane and to the region of the capsule adjacent to the basal surface of these fibers. Light microscope radioautographs of the lens capsule at later time intervals revealed that by 1 month after injection the diffuse reaction had disappeared, and only the strongly labeled band remained. By 14.5 months after injection, this band had migrated partially across the lens capsule, but the capsule itself had increased considerably in thickness. On the other hand, the distance between the labeled band and the free edge of the capsule had decreased from that seen at the time of injection.
Myocardial cell relationships during morphogenesis in normal and cardiac lethal mutant axolotls, Ambystoma mexicanum
Authors: Fransen Margaret E. , Lemanski Larry F. 
Published: February 2005

AbstractSarcomere formation has been shown to be deficient in the myocardium of axolotl embryos homozygous for the recessive cardiac lethal gene c. We examined the developing hearts of normal and cardiac mutant embryos from tailbud stage 33 to posthatching stage 43 by scanning electron microscopy in order to determine whether that deficiency has any effect on heart morphogenesis. Specifically, we investigated the relationships of myocardial cells during the formation of the heart tube (stage 33), the initiation of dextral looping (stages 34–36), and the subsequent flexure of the elongating heart (stages 38–43). In addition, we compared the morphogenetic events in the axolotl to the published accounts of comparable stages in the chick embryo.In the axolotl (stage 33), changes in cell shape and orientation accompany the closure of the myocardial trough to form the tubular heart. The ventral mesocardium persists longer in the axolotl embryo than in the chick and appears to contribute to the asymmetry of dextral looping (stages 34–36) in two ways. First, as a persisting structure it places constraints on the simple elongation of the heart tube and the ability of the heart to bend. Second, after it is resorbed, the ventral myocardial cells that contributed to it are identifiable by their orientation, which is orthogonal to adjacent cells: a potential source of shearing effects. Cardiac lethal mutant embryos behave identically during these events, indicating that functional sarcomeres are not necessary to these processes. The absence of dynamic apical myocardial membrane changes, characteristic of the chick embryo (Hamburger and Hamilton stages 9–11), suggests that sudden hydration of the cardiac jelly is less likely to be a major factor in axolotl cardiac morphogenesis.Subsequent flexure (stages 38–43) of the axolotl heart is the same in normal and cardiac lethal mutant embryos as the myocardial tube lengthens within the confines of a pericardial cavity of fixed length. However, the cardiac mutant begins to exhibit abnormalities at this time. The lack of trabeculation (normally beginning at stage 37) in the mutant ventricle is evident at the same time as an increase in myocardial surface area, manifest in extra bends of the heart tube at stage 39. Nonbeating mutant hearts (stage 41) have an abnormally large diameter in the atrioventricular region, possibly the result of the accumulation of ascites fluid. In addition, mutant myocardial cells have a larger apical surface area compared to normals.