摘要:

AbstractThe capsular ligaments of the human hip joint were submitted to exact morphological analysis, and they proved to be multiple and numerous. We have described various ligamentous systems and their interconnections, and have suggested new terminologies and systematics. The ligaments were subjected to functional analysis by means of measuring strips to determine the positions in which the ligaments are taut. The ligament systems were all found to serve a restrictive function, and various parts of the apparatus restricted all possible movements in the hip joint. Extension is restricted by the medial iliofemoral complex, abduction by the pubofemoral ligament, and adduction by the posterior coxal ligaments and by the superior ischiofemoral ligament. Flexion is restricted by the inferior ischiofemoral ligaments, inward rotation by the superior ischiofemoral ligament, and outward rotation by the lateral iliofemoral complex. Only the ligament of the femoral head is unable to exert a restricting function, despite reaching a state of tension in extreme adduction.

ISSN:0002-9106    

DOI:10.1002/aja.1001920102

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractGeneral models of cell activation implicate Ca2+conductance as pivotal in conveying transmembrane signals. During embryonic development, both cell migration and differentiation are influenced by changes in Ca2+; and, as a consequence, the modulation of Ca2+is important in the control of many morphogenetic processes. Because Ca2+conductance may be regulated at voltage‐dependent Ca2+channels (VDCCs), we investigated whether neural crest cells develop VDCCs and, if so, whether they function in regulating migration and establishing cytomorphology. Autoradiography indicates that neural crest cells in vitro develop‐L‐type Ca2+channels during migration and differentiation. Blockage of these channels by verapamil, both in vivo and in vitro, leads to a dramatic and reversible inhibition of neural crest migration. Alterations are manifest in vitro in cell‐to‐cell and cell‐to‐substratum contact and in the organization of the actin cytoskeleton. In whole embryos, verapamil or nifedipine inhibits pigment pattern formation. Moreover. blockage of the ‐L‐type Ca2+channels in whole embryos or cultures, after cells have already migrated and differentiated, results in a significant change in individual cell shape and in the overall pigment cell pattern, suggesting further that maintenance of the differentiated state also requires regulation at the ‐L‐type Ca2+channel. Since certain aspects of neural crest adhesion and cytoskeletal function are dependent on Ca2+, it is suggested that interactions that regulate the availability of Ca2+through the VDCC may provide coordinate control of motile and adhesive interactions at the cell

ISSN:0002-9106    

DOI:10.1002/aja.1001920103

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractCurrently, the diagnostic interpretation of magnetic resonance (MR) images requires that radiologists integrate specific tissue contrast information from several different images obtained at the same anatomic slice position. Each of these images has its own unique tissue contrast patterns which are based on the image acquisition parameters (pulse sequence) selected. The complex contrast patterns observable in these images reflect the inherent biophysical characteristics of the tissues and fluids present in the imaged section. In an effort to increase the diagnostic accuracy and efficiency of MR image interpretation, we have generated color composite images from quantitatively analyzed achromatic MR images of the brain, obtained while utilizing different pulse sequences. By using a DEC Micro VAX II computer with Interactive Digital Language (IDL), this color display method has been applied to images obtained from General Electric Signa and Siemens Magnatom imagers. For this study, our image sets included T1‐weighted, T2‐weighted, and proton density spin echo sequences as well as both high and low flip angle gradient echo sequences. Advantages of our color composite methods, in contrast to many other image processing techniques that have been described, are that minimal information is lost, computer misclassification of tissues is avoided, and the conspicuity of specific tissues is enhanced. Furthermore, with this method it is possible to produce composite images whose color renditions approach a natural anatomic tissue appearance. Availability of these color composites to radiologists may improve the efficiency and accuracy of the diagnostic interpretation of MR ima

ISSN:0002-9106    

DOI:10.1002/aja.1001920104

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractOsteoclasts collected from the long bones of mice were cultured on dentin slices. To identify osteoclasts, the tartrate‐resistant acid phosphatase (TRACPase) activity of cultured cells was histochemically examined by the azo dye method. The TRACPase‐positive cells could be distinguished from other cells by light microscopy. The cells were sectioned by alternating semithin and ultrathin sections to observe their ultrastructure and three‐dimensional structure.TRACPase activity was detected both in multinucleated osteoclasts and in mononuclear cells. Most of the mononuclear TRACPase‐positive cells had features similar to preosteoclasts. A mononuclear TRACPase‐positive cell was a ruffled border and clear zone was reconstructed three‐dimensionally by NIKON COSMOZONE 2SA. The reconstruction showed that this cell possessed a large clear zone and small ruffled border. Under the ruffled border, no lacuna was apparent; but there was disruption of the dentin surface. The results suggest that this cell was a mononuclear osteoclast and that it might have been in the process of making a

ISSN:0002-9106    

DOI:10.1002/aja.1001920105

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractPellets of mineralized and demineralized bone and a composite mixture of mineralized and demineralized, devitalized bone particles were implanted subcutaneously on the dorsal body wall of young adult rats. Two weeks post‐implantation, the pellets were removed and processed for histochemical and morphological analyses. Rat proximal tibia was also processed for evaluation. The levels of tartrate‐resistant acid phosphatase (TRAP) activity in the multinucleated giant cells (MNGCs) from each of the three implants and from osteoclasts were assessed using an image analyzer. The osteoclasts from the proximal tibia and the majority of MNGCs from the demineralized implants demonstrated high levels of TRAP activity. MNGCs from the mineralized implants showed either a low level or absence of TRAP activity. Most MNGCs from the composite implants exhibited a low level of TRAP activity; however, there was a population of cells that demonstrated a high level of reaction product, similar to that seen in the tibia and demineralized implant. Morphologically, osteoclasts from the proximal tibia and from the osteogenic demineralized implant exhibited ruffled borders. A small population of MNGCs from the composite implant also revealed osteoclastic features. In summary, MNGCs from the mineralized implant did not exhibit a level of TRAP reaction product or morphology similar to osteoclasts, while the majority of cells from the demineralized implant and a subpopulation of the MNGCs elicited by the composite implant did demonstrate TRAP expression and morphology similar to osteoclasts. The expression of osteoclastic characteristics in cells at an ectopic site may be dependent on accessory signals from the skeletal microenvironment; such signals appear to be absent from or incomplete in the mineralized implants but appear to be present when demineralized bone particles are implan

ISSN:0002-9106    

DOI:10.1002/aja.1001920106

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractA morphological, electron microscopic, and biochemical study was undertaken to analyze the genesis of hadacidin‐induced cleft palate in hamster fetuses. Gross and light microscopic observations indicated that hadacidin affected the growth of vertical palatal shelves to induce cleft palate. Electron microscopic observations showed that initial hadacidin‐induced changes were seen in the mesenchymal cells. Within 12 hr of drug administration, the perinuclear space was swollen and a lysosomal response injury was evident in the mesenchymal cells. Subsequently, 24 hr after hadacidin treatment, lysosomes appeared in the epithelial cells; changes were also seen in the basal lamina which included separation of the lamina densa from the basal cells, duplication of lamina densa, and complete loss of basal lamina. Between 36 and 42 hr post‐treatment, the cellular and basal lamina changes subsided, and the epithelium of vertical shelves underwent stratification. Biochemical determination of enzyme acid phosphatase indicated that the levels of enzyme activity in both the control and treated palatal tissues corresponded to the appearance of lysosomes. Measurement of cAMP levels suggested that the peak activity of cAMP corresponded to that of enzyme acid phosphatase and cell injury. The cAMP activity in hadacidin‐injured cells, however, was significantly lower in comparison to that of the dying cells of control palates. Hadacidin treatment also affected DNA synthesis in the developing primordia of the palate. It was suggested that hadacidin injures the precursor cells of the palate prior to the appearance of the primordia, and subsequently affects their proliferative behavior, stunting the vertical growth of the palatal shelves and inducing a cleft

ISSN:0002-9106    

DOI:10.1002/aja.1001920107

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractPalatal taste buds of perihatching chicks were examined by electron microscopy. Four intragemmal cell types were characterized.(1)Light: with voluminous, electron‐lucent cytoplasm containing scattered free ribosomes, rough and smooth endoplasmic reticulum, plump mitochondria, sparse perinuclear filaments, occasional Golgi bodies, and numerous clear and dense‐cored vesicles. Clear vesicles sometimes aggregate in a presynaptic‐like configuration apposed to an axonal profile. These cells contained large, spherical, uniformly granular nuclei with one nucleolus. (2)Dark: with dense cytoplasm containing filamentous bundles surrounding the nucleus, occasional clear vesicles, centrioles, rough endoplasmic reticulum, and compact mitochrondria. The apical cytoplasm noticeably lacks dense secretory granules. Irregular to lobulated nuclei are densely granular, and contain scattered clumps of chromatin, adhering especially to the inner leaflet of the nuclear membrane, and at least one nucleolus. Cytoplasmic extensions of dark cells envelop other intragemmal cell types and nerve fibers. Light and dark cells project microvilli into the taste pore. (3)Intermediate: contain gradations of features of light and dark cells. (4)Basal: darker than the other intragemmal cell types and confined to the ventral bud region. Putative afferent synapses in relation to light cells, and axo‐axonal contacts are described. While the appearance of axo‐axonal contacts may be a transient developmental event, other bud features are consonant with observations in adult chickens and suggest that the peripheral gustatory apparatus is mature at hatching in this precocial avia

ISSN:0002-9106    

DOI:10.1002/aja.1001920108

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractIt has been demonstrated that the septation of the outflow tract of the heart is formed by the cardiac neural crest. Ablation of this region of the neural crest prior to its migration from the neural fold results in anomalies of the outflow and inflow tracts of the heart and the aortic arch arteries. The objective of this study was to examine the migration and distribution of these neural crest cells from the pharyngeal arches into the outflow region of the heart during avian embryonic development. Chimeras were constructed in which each region of the premigratory cardiac neural crest from quail embryos was implanted into the corresponding area in chick embryos. The transplantations were done unilaterally on each side and bilaterally. The quail‐chick chimeras were sacrificed between Hamburger‐Hamilton stages 18 and 25, and the pharyngeal region and outflow tract were examined in serial paraffin sections to determine the distribution pattern of quail cells at each stage. The neural crest cells derived from the presumptive arch 3 and 4 regions of the neuraxis occupied mainly pharyngeal arches 3 and 4 respectively, although minor populations could be seen in pharyngeal arches 2 and 6. The neural crest cells migrating from the presumptive arch 6 region were seen mainly in pharyngeal arch 6, but they also populated pharyngeal arches 3 and 4. Clusters of quail neural crest cells were found in the distal outflow tract at stage

ISSN:0002-9106    

DOI:10.1002/aja.1001920109

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractIn anuran amphibians, the specific color pattern of the skin is expressed after metamorphosis, and its formation involves pigment cell migrations. Pigment cells are differently distributed in the tadpole, larval, and froglet skin. To learn more about their fate during metamorphic climax and in the young froglet, we focused our attention on the different localizations of larval melanophores and iridophores in the ventral skin ofRana esculentabefore and during skin homing. Localizations of melanophores and iridophores can be elucidated at the developmental stages suggested by Taylor and Kollros (TK stages).At TK stage II (during early premetamorphosis), large melanophores beneath the larval skin are detected. At TK stage X, dispersed melanophores lie under bundles of muscular striated fibrils near the larval skin; they are also observed at the vascular level. At TK stage XVII (prometamorphosis), melanophores are extended on the inner side of the basement lamellar collagen. At the end of prometamorphosis, iridophores are located with melanophores in the separating space between attached basement collagen and derived basement collagen. At TK stage XX (earlier climax), melanophores and iridophores are detected inside the upper extremities of fractures opened in the derived basement collagen. At TK stage XXIV (later climax), both types of larval pigment cells are observed in the inner extremities of breaks derived from the fractures. During climax, these pigment cells occupy the well‐formed breaks. At TK stage XXV in young froglet, the pigment cells remain alone in the breaks formed in the derived basement collagen.Briefly, breaks in the basement lamellar collagen are opened by invading cell processes of mesenchymal cells. The cells move through the fractures toward the epidermis, followed in later stages by melanophores and iridophore

ISSN:0002-9106    

DOI:10.1002/aja.1001920110

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

ISSN:0002-9106    

DOI:10.1002/aja.1001920101

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY