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  • 1
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 143 (1974), S. 77-105 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The termite gut flagellates are of interest because of their unusual motile organelles, their ability to digest cellulose, and their symbiotic relationship with prokaryotes inhabiting the insect gut. This report provides a detailed ultrastructural description of Pyrsonympha from the hind-gut of Reticulitermes flavipes.The motile axostyle is composed of 2,000-4,000 microtubules connected by cross-bridges. At its anterior end, the axostyle is associated with a “primary row” of microtubules which is associated with a fibrous network. The “primary row” is embedded in a large mass of amorphous, electron-dense material occupying the furthest anterior end of the cell. The basal bodies of the eight flagella are also embedded in this presumptive microtubule-organizing center. The flagella are associated with the cell surface throughout their length. Isolation and reactivation of the axostyle has demonstrated that although ATP dependent motility is inherent in the structure of the axostyle, its proper control may be mediated by the attachment of the axostyle to structures at the anterior end of the cell.Pyrsonympha lacks morphologically distinguishable mitochondria and Golgi complexes. The cell surface is covered by unique, previously underscribed, tubular specializations. Symbiotic microorganisms are observed associated with the cell surface and within the cytoplasm.Wood particles are taken up from the gut fluid by large phagocytic vacuoles formed at the posterior end of the cell. Even during the process of breakdown, the wood is always enclosed within the membrane of the phagocytic vacuole.The Pyrsonympha from Reticulitermes flavipes are not attached to the lining of the hind-gut and do not contain an attachment organelle, unlike the Pyrsonympha from other species of Reticulitermes.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 140 (1973), S. 381-395 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The dissected tooth bearing bones of 20 specimens of Amia calva (Pisces:Holostei) ranging from the third to tenth season have been examined radiographically and in alizarin red S stained and cleared specimens. Although forms of alternate (1:1) tooth series replacement (sensu Edmund, '60) were frequently observed, even in the youngest, immature specimens, many examples of irregular replacement were recorded. In several bones, the maxillae in particular, series with every third (2:1) or fourth (3:1) tooth replacing were seen and possible patterns of 2:2, were recorded. It is concluded that these data are not consistent with the Zahnreihen concept but support a morphogenic field concept of tooth development.
    Additional Material: 5 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 131 (1970), S. 359-382 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Small swellings near the base of the radial vein in each fore wing of the green lacewing, Chrysopa carnea, resemble typical insect tympanal organs, but some important differences are apparent. The swellings are bounded dorsally and laterally by thick cuticle and ventrally by thin, membranous cuticle. The ventral membrane is formed by a single, thin sheet of exocuticle with flattened hypodermis internally, but lacks the tracheal component that forms part of the tympanum in the typical insect tympanal organ. The portion of the membrane beneath each swelling is rippled while proximally it is smooth. In contrast to typical insect tympanal organs, the swellings in C. carnea are largely fluid-filled since an unexpanded trachea runs through each organ. A distal and a proximal chordotonal organ composed of typical chordotonal sensory units are associated with each swelling. The distal organ contains from five to seven units while the proximal organ is composed of from 18 to 20 units. Each sensory unit is composed of three readily identifiable cells. Distally, an attachment cell unites with the membrane and is contiguous with the scolopale cell, which surrounds the dendrite of the bipolar neuron. On the basis of the morphological evidence, one would not expect these swellings to function as sound receptors. However, the results of physiological and behavioral experiments, presented elsewhere, show that these organs are receptors for ultrasound.
    Additional Material: 1 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 130 (1970), S. 501-509 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Although there are many reports of tooth replacement patterns in lower vertebrates, few show the range of pattern to be found in a number of similar aged specimens of one species. Fifteen specimens of Caiman sclerops, head length 4-5 cms, were examined by a radiographic technique and their tooth replacement patterns analysed. Whole head radiography and dissected head radiographs were compared and the resulting tooth replacement waves were found to be comparable. Wave replacement (sensu Edmund, '60) in odd and even tooth positions in the tooth row was observed in all the specimens examined. Whereas most waves passed in a cephalad direction, wave reversal (caudad) was also observed, particularly in the anterior parts of the jaws. In some specimens simple alternation in tooth replacement was observed, particularly in the mid-portion of each quadrant. The smooth, age-related change-over from cephalad to caudad demonstrated by Edmund ('62) in captive Alligator mississippiensis was not observed in wild specimens of Caiman sclerops.
    Additional Material: 4 Ill.
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  • 5
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Although there are a number of studies on tooth replacement patterns in lower vertebrates, most do not indicate whether this process is continuous throughout the year or is affected by either breeding or seasonal cycles. We have surveyed the replacement patterns found in living and specifically killed Necturus maculosus (Amphibia: Proteidae) to determine the nature of their variation throughout the year prior to investigating possible controlling mechanisms of the formation and eruption of amphibian teeth. Some animals (34), kept in a large outside tank, were killed at monthly intervals and their tooth-bearing bones radiographed using a modification of the technique previously described (Miller and Radnor, '70). Other animals (9), kept at 4°C, were anesthetized with tricaine methanesulphonate (M.S. 222), and wax impressions taken with beading (carding) wax of the functioning teeth at regular intervals. Animals examined in the late spring and summer (25) showed no signs of active tooth replacement. Small replacement teeth visible beneath each functioning tooth enlarged only slightly throughout the summer. In early and late fall some functioning teeth were lost and replacement teeth grew and erupted to replace them. Replacement patterns were very irregular and classical alternate form rarely seen. In a number of animals the replacement series was formed from every third tooth. Animals kept constantly at 4°C showed no replacement phenomena. Patterns varied between the different bones of the jaws and did not support the Zahnreihe concept of Edmund ('60).
    Additional Material: 7 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 84 (1974), S. 429-444 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Cell membrane antigens serve as recognition codes for normal cell functions (substrate transport, cell-cell interaction, etc.). Changes in antigen-function activity are associated with ontogeny and speciation. Some prenatal antigenic configurations are postulated to provide host protection during early development.
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