Search Results - (Author, Cooperation:B. K. Hall)

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  1. 1
    T. Hashimshony ; M. Feder ; M. Levin ; B. K. Hall ; I. Yanai
    Nature Publishing Group (NPG)
    Published 2014
    Staff View
    Publication Date:
    2014-12-10
    Publisher:
    Nature Publishing Group (NPG)
    Print ISSN:
    0028-0836
    Electronic ISSN:
    1476-4687
    Topics:
    Biology
    Chemistry and Pharmacology
    Medicine
    Natural Sciences in General
    Physics
    Keywords:
    Animals ; Caenorhabditis elegans/cytology/*embryology/*genetics ; Cell Lineage ; Eating ; Ectoderm/cytology/embryology/metabolism ; Endoderm/cytology/embryology/*metabolism ; *Evolution, Molecular ; Gene Expression Profiling ; Gene Expression Regulation, Developmental/*genetics ; Mesoderm/cytology/embryology/metabolism ; Models, Biological ; Porifera/cytology/embryology/genetics ; Sea Anemones/cytology/embryology/genetics ; *Spatio-Temporal Analysis ; Time Factors ; Transcriptome/*genetics ; Xenopus/embryology/genetics
    Published by:
    Latest Papers from Table of Contents or Articles in Press
  2. 2
    K. B. Hall
    Nature Publishing Group (NPG)
    Published 2014
    Staff View
    Publication Date:
    2014-02-14
    Publisher:
    Nature Publishing Group (NPG)
    Print ISSN:
    0028-0836
    Electronic ISSN:
    1476-4687
    Topics:
    Biology
    Chemistry and Pharmacology
    Medicine
    Natural Sciences in General
    Physics
    Keywords:
    *Molecular Dynamics Simulation ; RNA, Ribosomal, 16S/*chemistry/*metabolism ; Ribosomal Proteins/*metabolism ; Ribosome Subunits, Small, Bacterial/*chemistry/*metabolism
    Published by:
    Latest Papers from Table of Contents or Articles in Press
  3. 3
    Squier, C. A. ; Cox, P. ; Hall, B. K.

    Oxford, UK : Blackwell Publishing Ltd
    Published 1986
    Staff View
    ISSN:
    1600-0714
    Source:
    Blackwell Publishing Journal Backfiles 1879-2005
    Topics:
    Medicine
    Notes:
    There is evidence for synergy between tobacco and alcohol in the etiology of oral cancer but the reason for such an effect is unclear. One possible explanation is that alcohol enhances the penetration of carcinogens through the oral lining. We measured the permeability in vitro of three regions of porcine oral mucosa to the tobacco associated carcinogen, nitrosonornicotine (NNN) alone and in the presence of 5% or 50% ethanol. 50% ethanol did not significantly alter the permeability of oral mucosa to NNN except for buccal mucosa, where it was reduced. However, there was a significant increase in the permeability of gingiva and floor of mouth mucosa (but not buccal mucosa) in the presence of 5% ethanol; this increase occurred after far shorter exposures for floor of mouth than for gingiva. These results accord well with studies showing (a) that the Door of mouth is a “high risk area” for oral carcinoma and (b) that there is an increased relative risk of oral cancer for heavy smokers and drinkers and, in particular, for those individuals who consume beverages with a low alcohol content.
    Type of Medium:
    Electronic Resource
    URL:
    Articles: DFG German National Licenses
  4. 4
    Squier, C. A. ; Hall, B. K.

    Oxford, UK : Blackwell Publishing Ltd
    Published 1985
    Staff View
    ISSN:
    1600-0714
    Source:
    Blackwell Publishing Journal Backfiles 1879-2005
    Topics:
    Medicine
    Notes:
    An epithelial hyperplasia is one of the reactions of skin and oral mucosa to chemical and mechanical insult. It is usually assumed that this reaction produces a more effective epithelial harrier, but there is no information as to whether a less permeable (issue results. To examine this question, hyperplasia was induced in the cheek pouches of hamsters by either chemical treatment with 0.0025% TPA in acetone or by mechanical abrasion with a rotating mop; untreated hamsters served as controls. The animals were killed and the cheek pouches were removed, mounted in diffusion chambers and the permeability to labelled water and horseradish peroxidase (IIRPO) determined. The results showed that higher values were obtained for the permeability constant of hyperplastic epithelia than for that of control tissue, suggesting that an increased epithelial thickness is not necessarily associated with an improved permeability barrier function. The presence of an inferior barrier layer in hyperplastic epithelia may be related to the increased rate of turnover of this tissue.
    Type of Medium:
    Electronic Resource
    URL:
    Articles: DFG German National Licenses
  5. 5
    Witten, P. E. ; Holliday, L. S. ; Delling, G. ; Hall, B. K.

    Oxford, UK : Blackwell Publishing Ltd
    Published 1999
    Staff View
    ISSN:
    1095-8649
    Source:
    Blackwell Publishing Journal Backfiles 1879-2005
    Topics:
    Biology
    Notes:
    Poly-and monoclonal antibodies, raised against mammalian membrane-bound proton pump (V-ATPase) were applied to the bone-resorbing cells of Oreochromis niloticus to clarify if osteoclasts of an advanced teleost species display V-ATPase, a key enzyme in the process of bone resorption. All antibodies labelled cells at known sites of bone resorption, the endosteal bone surfaces surrounding the tooth anlagen. The best results were achieved with a monoclonal antibody (E11). Although the majority of labelled cells were flat and mononucleated, the occurrence of V-ATPase in these cells indicates that they function as active bone-resorbing cells. The monoclonal antibody E11 was also applied successfully to monocytes, cells that are believed to be related most closely to osteoclasts. The assignment of V-ATPase to boneresorbing cells of O. niloticus was confirmed by application of the additional osteoclast markers, tartrate-resistant acid phosphatase (TRAP) and tartrate-resistant ATPase (TraATPase). Co-expression of V-ATPase, TRAP and TraATPase in fish osteoclasts is demonstrated for the first time.
    Type of Medium:
    Electronic Resource
    URL:
    Articles: DFG German National Licenses
  6. 6
    Witten, P. E. ; Villwock, W. ; Peters, N. ; Hall, B. K.

    Oxford, UK : Blackwell Science, Ltd
    Published 2000
    Staff View
    ISSN:
    1439-0426
    Source:
    Blackwell Publishing Journal Backfiles 1879-2005
    Topics:
    Biology
    Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes:
    The present study considers the important role of bone resorption for bone growth in general, and aims to clarify if and how bone resorption contributes to the skeletal development of carp, Cyprinus carpio L., a teleost species with ‘normal’ osteocyte-containing (cellular) bone. To ensure the identification of osteoclasts and sites of bone resorption independently from the morphology of the bony cells, bones were studied by histological procedures, and by demonstration of the enzymes which serve as osteoclast markers, viz. tartrate resistant acid phosphatase (TRAP), ATPase and a vacuolar proton pump. Two types of bone-resorbing cells were observed in juvenile carp: (1) multinucleated giant cells displaying morphological and biochemical attributes which are known from mammalian osteoclasts; and (b) flat cells which lack a visible ruffled border and for which identification requires the performance of enzyme histochemical procedures. Bone resorption performed by osteoclasts mainly occurs at endosteal bone surfaces. To a lesser extent, bone resorption also takes place at periosteal bone surfaces, but without an apparent connection to bone growth. The latter observation, and the occurrence of bone remodelling, suggest that the endoskeleton of juvenile carp might be involved in mineral metabolism. Morphological differences and biochemical similarities to bone resorption in teleosts with acellular bone are discussed.
    Type of Medium:
    Electronic Resource
    URL:
    Articles: DFG German National Licenses
  7. 7
    Hall, B. K.
    Springer
    Published 1970
    Staff View
    ISSN:
    1432-0827
    Source:
    Springer Online Journal Archives 1860-2000
    Topics:
    Biology
    Medicine
    Physics
    Type of Medium:
    Electronic Resource
    URL:
    Articles: DFG German National Licenses
  8. 8
    Hall, B. K. ; Miyake, T.
    Springer
    Published 1992
    Staff View
    ISSN:
    1432-0568
    Keywords:
    Condensations ; Osteogenesis ; Chondrogenesis ; Mutants ; Morphology ; Membranous skeleton
    Source:
    Springer Online Journal Archives 1860-2000
    Topics:
    Medicine
    Notes:
    Summary Elements of the vertebrate skeleton are initiated as cell condensations, collectively termed the ‘membranous skeleton’ whether cartilages or bones by Grüneberg (1963). Condensations, which were identified as the basic cellular units in a recent model of morphological change in development and evolution (Atchley and Hall 1991) are reviewed in this paper. Condensations are initiated either by increased mitotic activity or by aggregation of cells towards a centre. Prechondrogenic (limb bud) and preosteogenic (scierai ossicle) condensations are discussed and contrasted. Both types of skeletogenic condensations arise following epithelial-mesenchymal interactions; condensations are identified as the first cellular product of such tissue interactions. Molecular characteristics of condensations are discussed, including peanut agglutinin lectin, which is used to visualize prechondrogenic condensations, and hyaluronan, hyaladherins, heparan sulphate proteoglycan, chondroitin sulphate proteoglycan, versican, tenascin, syndecan, N-CAM, alkaline phosphatase, retinoic acid and homeobox-containing genes. The importance for the initiation of chondrogenesis or osteogenesis of upper and lower limits to condensation size and the numbers of cells in a condensation are discussed, as illustrated by in vitro studies and by mutant embryos, including Talpid3 in the chick and Brachypod, Congenital hydrocephalus and Phocomelia in the mouse. Evidence that genes specific to the skeletal type are selectively activated at condensation is discussed, as is a recent model involving TGF-β and fibronectin in condensation formation. Condensations emerge as a pivotal stage in initiation of the vertebrate skeleton in embryonic development and in the modification of skeletal morphology during evolution.
    Type of Medium:
    Electronic Resource
    URL:
    Articles: DFG German National Licenses
  9. 9
    Taylor, L. H. ; Hall, B. K. ; Miyake, T. ; Cone, D. K.
    Springer
    Published 1994
    Staff View
    ISSN:
    1432-0568
    Keywords:
    Ectopic ossification ; Ossicles ; parasite infection ; Chondroid bone ; Bone
    Source:
    Springer Online Journal Archives 1860-2000
    Topics:
    Medicine
    Notes:
    Abstract This paper describes the development and tissues in mineralized ossicles in the musculature of Perca flavescens infected with metacercariae of the trematode Apophallus brevis. Analysis involved light microscopy, transmission and scanning electron microscopy, X-ray scanning electron microprobe analysis, and tetracycline labelling. Two to 14 days post-infection, fibroblast-like host cells stream towards the parasite cyst forming a fusiform cellular capsule. By 14 days post-infection the capsule differentiates into an inner hypertrophied layer, an extensive middle layer of fibroblast-like cells, and a thin outer layer of flattened fibroblast-like cells forming a fibrous sheath at the capsule/muscle interface. From 21–35 days post-infection, a bony tissue is deposited periosteally in an equatorial ring around the cyst. With time, additional tissue is secreted over the ring increasing its thickness and advancing the matrix front towards the poles of the ossicle. Plump osteoblast-like cells cover the developing ossicle and may become trapped within the matrix in lacunae encapsulated by collagen. By 63 days post-infection, medium-sized ossicles are morphologically similar to large cysts from perch captured in the wild; ovoid with two polarized canals, but lacking acellular or lamellar bone-like tissue. Mineralized ossicles contain calcium, phosphorus and oxygen. Large ossicles retrieved from perch given multiple doses of tetracycline revealed discrete fluorescent bands, indicative of incremental growth. Fully developed ossicles are composed of two skeletal tissues, an inner region of chondroid bone and an outer region of acellular, lamellar bone.
    Type of Medium:
    Electronic Resource
    URL:
    Articles: DFG German National Licenses
  10. 10
    Graveson, A. C. ; Hall, B. K.
    Springer
    Published 1995
    Staff View
    ISSN:
    1432-041X
    Keywords:
    Axolotl ; Neural crest ; Ambystoma mexicanum ; Cell migration ; Chondrogenesis
    Source:
    Springer Online Journal Archives 1860-2000
    Topics:
    Biology
    Notes:
    Abstract Based on results of transplantation experiments, it has long been believed that trunk neural crest cells are incapable of chondrogenesis. When pigmented trunk neural crest cells of Ambystoma mexicanum are transplanted to cranial levels of albino (a/a) embryos, the graft cells ultimately produce ectopic fins, but are incapable of following the chondrogenic cranial neural crest pathways. Therefore, heterotopic transplantation does not expose these cells to the same environment experienced by cranial neural crest cells, and is neither an adequate nor a sufficient test of chondrogenic potential. However, in vitro culture of trunk neural crest cells with pharyngeal endoderm does provide a direct test of chondrogenic ability. That cartilage does not form under these conditions demonstrates conclusively that trunk neural crest cells possess no chondrogenic potential.
    Type of Medium:
    Electronic Resource
    URL:
    Articles: DFG German National Licenses
  11. 11
    Hanken, J. ; Summers, C. H. ; Hall, B. K.
    Springer
    Published 1989
    Staff View
    ISSN:
    1420-9071
    Keywords:
    Morphological integration ; skull ; Anura ; thyroid hormone ; metamorphosis
    Source:
    Springer Online Journal Archives 1860-2000
    Topics:
    Biology
    Medicine
    Notes:
    Summary We examined the role of thyroid hormone in mediating morphological integration between cranial cartilage and bone during anuran metamorphosis. Exogenous T3 applied to premetamorphic tadpoles (Bombina orientalis) via intracranial implants of plastic micropellets precociously induced typical metamorphic changes in both tissues, but also dissociated the relative timing of developmental events between them. Morphological integration between the two primary cranial tissues is achieved in part by each tissue responding independently to endocrine factors and does not reflect a tight developmental coupling between them.
    Type of Medium:
    Electronic Resource
    URL:
    Articles: DFG German National Licenses
  12. 12
    Thorogood, P. V. ; Hall, B. K.
    Springer
    Published 1976
    Staff View
    ISSN:
    1432-0827
    Source:
    Springer Online Journal Archives 1860-2000
    Topics:
    Biology
    Medicine
    Physics
    Type of Medium:
    Electronic Resource
    URL:
    Articles: DFG German National Licenses
  13. 13
    Hall, B. K.
    Springer
    Published 1971
    Staff View
    ISSN:
    1432-0827
    Keywords:
    Bone ; Cartilage ; Differentiation ; Collagen ; β-aminopropionitrile
    Source:
    Springer Online Journal Archives 1860-2000
    Topics:
    Biology
    Medicine
    Physics
    Description / Table of Contents:
    Résumé L'injection d'embryons de poulet, incubés pendant neuf jours, avec du β-aminopropionitrile (BAPN), à des doses supérieures à 0,312 mg par embryon, empêche la formation de cartilage, normalement présent au niveau des os de membrane à partir du llème jour de l'inculation. L'hitsogenese de cette inhibition est décrite. BAPN augmente la propertion de collagène et diminue la synthèse des mucopolysaccharides acides, contenant de l'hesoxamine, au niveau des os de membrane. Le rapport entre les chainons tranversaux du collagène, sa solubilité, la synthèse des mucopolysaccharides acides et la stimulation mécanique (le facteur extrinsèque déclenchant la chondrogenèse dans le système) est discuté sous l'angle de la formation cartilagineuse sur les os de membrane, à partir de cellules souches.
    Abstract:
    Zusammenfassung Wird β-Aminopropionitrol (BAPN) in Dosen von über 0,312 mg/Embryo in 9 Tage inkubierte Hühnerembryonen injiziert, so wird die Bildung des normalerweise vom 11. Inkubationstag an auf dem Deckknochen vorliegenden Knorpels verhindert. Die Histogenese dieser Hemmung wird beschrieben. BAPN erhöhte den Anteil des löslichen Kollagens, ohne die Synthese des Totalkollagens zu verändern; es verminderte die Synthese der hexosaminhaltigen sauren Mucopolysaccharide innerhalb der Deckknochen. Die Diskussion betrifft die Beziehung zwischen der Quervernetzung des Kollagens, der Kollagenlöslichkeit, der Synthese von sauren Mucopolysacchariden und der mechanischen Stimulation (wobei der Extrinsicfaktor die Chondrogenese in diesem System auslöst) bei der Knorpelbildung aus den bipotentialen Keimzellen der Deckknochen.
    Notes:
    Abstract Injection into chick embryos incubated for nine days, of β-aminopropionitrile (BAPN) at doses above 0.312 mg/embryo prevented the formation of the cartilage normally present on the membrane bones from the eleventh day of incubation onwards. The histogenesis of this inhibition is described. BAPN increased the proportion of soluble collagen without altering total collagen synthesis and decreased the synthesis of hexosamine-containing acid mucopolysaccharides within the membrane bones. The relationship between cross-linking of collagen, collagen solubility, synthesis of acid mucopolysaccharides and mechanical stimulation (the extrinsic factor initiating chondrogenesis in this system) in the formation of cartilage from bipotential germinal cells on the membrane bones is discussed.
    Type of Medium:
    Electronic Resource
    URL:
    Articles: DFG German National Licenses
  14. 14
    Hall, B. K.
    Springer
    Published 1968
    Staff View
    ISSN:
    1432-119X
    Source:
    Springer Online Journal Archives 1860-2000
    Topics:
    Biology
    Medicine
    Notes:
    Summary The histochemistry of the adventitious cartilage of the chick has been studied and compared with both primary cartilage and the bone on which the adventitious cartilage develops. The distribution of DNA, RNA, collagen, acid mucopolysaccharide, mucoprotein, glycogen, lipid, alkaline phosphatase and inorganic phosphate has been studied. Adventitious cartilage was found to have the histochemistry of primary hypertrophic cartilage and to calcify. The appearance of lipid and alkaline phosphatase activity coincided with the onset of calcification. The proliferating osteogenic and chondrogenic cells of the chick embryo have been classified and compared histochemically. Collagen synthesis was found to be high in the osteogenic cells and acid mucopolysaccharide and mucoprotein synthesis high in the chondrogenic cells. It has been postulated that the morphogenetic switch from osteogenesis to adventitious chondrogenesis most probably involves a change in the rate of collagen and acid mucopolysaccharide synthesis by the germinal cells of the membrane bones.
    Type of Medium:
    Electronic Resource
    URL:
    Articles: DFG German National Licenses
  15. 15
    Hunt, I. ; Boutilier, R. G. ; Miyake, T. ; Hall, B. K.
    Springer
    Published 1996
    Staff View
    ISSN:
    1432-1793
    Source:
    Springer Online Journal Archives 1860-2000
    Topics:
    Biology
    Notes:
    Abstract The morphology and function of structures important to energy acquisition were studied from spawning to the stage of transformation of larva to pelagic juvenile in Atlantic cod, Gadus morhua L., from December 1991 to July 1992. Fertilized eggs produced by adult fish from two genetically discrete populations (Newfoundland and Scotian Shelf) were raised under similar conditions in the laboratory at temperatures of 5 and 10°C. Subsamples of larvae were removed from cultures daily for 10 d, and then less frequently, and fixed for light microscopy and scanning electron microscopy. Nine functional morphological “landmarks” important to feeding, respiration and locomotion were chosen from observation of 280 ind. These landmarks defined 12 major developmental stages, from hatching to the pelagic juvenile stage. One of the feeding landmarks, intestinal stage, varied as a function of age and size and the variance in development was higher at 10°C than at 5°C; Newfoundland larvae developed more complex intestines than did Scotian Shelf larvae. In addition, Newfoundland larvae had significantly higher growth rates than those of Scotian Shelf larvae. Despite the higher growth rates and greater structural complexity of the intestine in Newfoundland larvae, the rate of yolk utilization was not significantly different between Newfoundland and Scotian Shelf larvae. Staging of respiratory landmarks showed that the gill arches were probably used preferentially in feeding while respiration was cutaneous. The gills, operculum and gill rakers developed late in larval life and accompanied the transition from cutaneous to branchial respiration. In the yolk-sac period, development of feeding and respiratory structures may be largely genetically controlled. During exogenous feeding, extrinsic factors also become important, as shown by the size and age-independent variation in intestinal development of larval cod raised at different temperatures.
    Type of Medium:
    Electronic Resource
    URL:
    Articles: DFG German National Licenses
  16. 16
    Smith, S. L. ; Hall, B. K.
    Springer
    Published 1980
    Staff View
    ISSN:
    1432-1793
    Source:
    Springer Online Journal Archives 1860-2000
    Topics:
    Biology
    Notes:
    Abstract Standard autoradiographic techniques have been used to describe the temporal pattern in the transfer of radioactive carbon from the chlorophyte Tetraselmis suesica (Kylin) to females of the neritic copepod Temora longicornis (Müller, 1792). After 4 and 6 h exposure to labelled phytoplankton, silver grains were deposited only in the cells of the gut-wall. After 24 h exposure, grains were deposited in most tissues, with highest concentrations in cells of the gut-wall and in oocytes within the ovary. Experiments with Centropages typicus (Krøyer), Centropages hamatus (Lilljeborg), and Labidocera aestiva Wheeler demonstrated that much of the assimilated label was not turning over rapidly and that the amount of label assimilated was correlated with known food preferences of these species.
    Type of Medium:
    Electronic Resource
    URL:
    Articles: DFG German National Licenses
  17. 17
    Staff View
    ISSN:
    1432-1777
    Source:
    Springer Online Journal Archives 1860-2000
    Topics:
    Biology
    Medicine
    Notes:
    Abstract Using degenerate primer amplification of chromosomes microdissected from banded cytogenetic preparations, we constructed both whole chromosome painting probes for mouse Chromosomes (Chrs) 1, 2, 3, and 11 and a centromere probe that strongly paints most mouse centromeres. We also amplified a Robertsonian translocation chromosome microdissected from unstained preparations to construct a painting probe for Chrs 9 and 19. The chromosomes probes uniformly painted the respective chromosomes of origin. We demonstrated the utility of the Chr 11 probe in aberration analysis by staining mutants that we had previously identified as containing a Chr 11 translocation, and in some mutant cell lines we observed chromosome rearrangements not previously detected in stained cytogenetic preparations. The technology of microdissection and amplification applies to all mouse chromosomes or to specific subchromosomal regions and will be useful in mouse genetics, in aberration analysis, and for chromosome identification.
    Type of Medium:
    Electronic Resource
    URL:
    Articles: DFG German National Licenses
  18. 18
    Hall, B. K. ; Jacobson, H. N.

    New York, NY [u.a.] : Wiley-Blackwell
    Published 1975
    Staff View
    ISSN:
    0003-276X
    Keywords:
    Life and Medical Sciences ; Cell & Developmental Biology
    Source:
    Wiley InterScience Backfile Collection 1832-2000
    Topics:
    Medicine
    Notes:
    Repair of a fractured membrane bone, the quadratojugal (QJ), has been studied in the newly hatched chick. Complete open fractures never united by bony fusion, even in birds maintained for six months post-fracture. Extraperiosteal connective tissue invaded the fracture gap and formed thick fibrous bundles which stabilised the fracture. Cartilage of two types formed on these bones. One was derived from periosteal cells and the other from osteoblasts or osteocytes. Considerably more cartilage formed in bones partially fractured than in those completely fractured. The “periosteal” cartilage did not form if the periosteum was removed at the time the bone was fractured. This was because, although the fibrous layer of the periosteum regenerated, the cambial layer did not. Metaplastic cartilage did form in the absence of the periosteum.Isolating fractured bones within polyethylene or glass tubes prevented accumulation of a blastema between the bony fragments. Cartilage did not form in side the tubes but did form where the ends of the tubes abutted onto the bones.Large defects in the bones (4 mm gaps, 4 mm of bone in the place of the QJ) healed via fibrous union with minimal osteogenesis and no chondrogenesis.Severing M. depressor mandibulae at the time the bone was fractured inhibited chondrogenesis, favoured osteogenesis and resulted in development of a pseudarthrosis.The potential for differentiation of the cells of the QJ and the role of adjacent tissues as they related to repair of the fracture was discussed, and the ability of cells from membrane bones to become chondrogenic emphasized.
    Additional Material:
    1 Ill.
    Type of Medium:
    Electronic Resource
    URL:
    Articles: DFG German National Licenses
  19. 19
    Hall, B. K. ; Girouard, R. J.

    New York, NY [u.a.] : Wiley-Blackwell
    Published 1973
    Staff View
    ISSN:
    0003-276X
    Keywords:
    Life and Medical Sciences ; Cell & Developmental Biology
    Source:
    Wiley InterScience Backfile Collection 1832-2000
    Topics:
    Medicine
    Notes:
    Chick embryos were hypophysectomized by partial decapitation at 33 hours of incubation and the subsequent morphogenesis and growth of the whole embryo and the growth, histology and histochemistry of the tibia studied.Twenty-five percent of the increase in body weight which normally occurs between 12 and 18 days of incubation and 60% of the normal growth of the tibia over the same period failed to occur in the hypophysectomized embryos. Histological studies indicated that the diminished skeletal growth resulted from reduced proliferation of chondroblasts within the epiphyseal growth zone and from reduced deposition of acid mucopolysaccharides into the cartilaginous matrix. The differentiation and hypertrophy of the chondrocytes produced in the hypophysectomized embryos was not affected. Therefore, the pituitary gland exerts considerable control over the development of the cartilaginous skeleton in the embryonic chick.Osteogenesis was reduced as a consequence of the reduced chondrogenesis in the long bones from the hypophysectomized embryos.
    Additional Material:
    1 Ill.
    Type of Medium:
    Electronic Resource
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    Articles: DFG German National Licenses
  20. 20
    Hall, B. K.

    New York, NY [u.a.] : Wiley-Blackwell
    Published 1973
    Staff View
    ISSN:
    0003-276X
    Keywords:
    Life and Medical Sciences ; Cell & Developmental Biology
    Source:
    Wiley InterScience Backfile Collection 1832-2000
    Topics:
    Medicine
    Notes:
    Embryonic chicks were treated with exogenous L-thyroxine or with thiourea at eight days of incubation and the subsequent development of the tibia studied.The weight of the tibia was 62% lower than that from normal embryos, and the length of the tibia 24% below normal in the embryos treated with thiourea. This reduced rate of growth was shown to be due to a reduction in the rate of maturation of chondroblasts into chondrocytes, reduced chondrocyte hypertrophy and defective deposition of acid mucopolysaccharide into the cartilage matrix. Osteogenesis per se was unaffected. It was concluded that thyroxine plays a role in the control of chondrocyte maturation and in cartilage matrix production during normal development.The epiphyses of the tibiae from the embryos treated with thiourea were extensively eroded, invaded by marrow and more fragile than those from untreated embryos, indicating that thyroxine is essential for the maintenance of the integrity of the articular cartilage. An abnormal core of bone developed within the proximal epiphysis of these embryos.Exogenous thyroxine at concentrations as low as 100 pg/embryo also reduced the growth of the tibia below that seen in untreated embryos. Evidently the cells of the skeleton are sensitive to both lowered and increased levels of circulating thyroxine.
    Additional Material:
    3 Tab.
    Type of Medium:
    Electronic Resource
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    Articles: DFG German National Licenses