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  • 1
    Electronic Resource
    Electronic Resource
    Mapping the origin of the avian enteric nervous system with a retroviral marker (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Developmental Dynamics 201 (1994), S. 236-244 
    Details
    ISSN: 1058-8388
    Keywords: Spleen necrosis virus ; Enteric nervous system ; Beta-galactosidase ; Chick embryo ; Somite ; Neural crest ; lac Z gene ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The enteric nervous system is largely formed from the vagal neural crest which arises from the neuroaxis between somites 1 - 7. In order to evaluate the contribution of different regions of the vagal crest to the enteric nervous system, we marked crest cells by injecting somites 1 - 10 with a replication-defective spleen necrosis virus vector which contains the marker gene lacZ. After incubation in X-gal, lacZ-positive blue cells were found in the wall of the gut in three locations. Most were found at the peripheral edge of the developing circular muscle and within the developing submucosa, sites characteristic of developing ganglia. LacZ-positive cells in these ganglionic sites were always surrounded by HNK-1 immunostained cells, confirming their neural crest origin. LacZ-positive cells were also seen in a third location, the circular muscle layer of the esophagus and crop, and were separated from the HNK-1 positive ganglionic elements. These cells in the circular muscle are probably muscle cells derived from labeled mesodermal cells of the somite. Injection of somites 3, 4, 5, and 6 resulted in the largest percentage of preparations with lacZ-positive crest-derived cells and in the largest number of positive cells in the gut. After injection of these somites, lacZ-positive crest-derived cells were found in all regions of the gut from the proventriculus to the rectum. Very few positive crest-derived cells were found in the esophagus. Injection of somites 1, 2, and 7 resulted in a smaller percentage of preparations with positive crest-derived cells and in a smaller number of positive crest-derived cells, which were confined to the fore and midgut. The gizzard was the gut region most frequently containing labeled cells and the rectum was the region least frequently containing such cells. This suggests that the number of crest cells available for colonization of the gut decreases as the distance from the gizzard increases. We conclude that the region of the neuroaxis between somites 3 - 6 is the major source of crest cells to the gut and that crest cells from different segments of the neuroaxis do not appear to be segregated to different regions of the gut. © 1994 Wiley-Liss, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aja.1002010307
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  • 2
    Electronic Resource
    Electronic Resource
    Clonal analysis of cardiac morphogenesis in the chicken embryo using a replication-defective retrovirus: I. Formation of the ventricular myocardium (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 193 (1992), S. 11-23 
    Details
    ISSN: 0002-9106
    Keywords: Heart ; Development ; Cell lineage ; Myocardium ; Cardiac myocyte ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Cells of the precardiac mesoderm (stages 4-6) and dividing myocytes of early hearts (stages 10-15) were tagged with a replication-incompetent retrovirus (CXL) (Mikawa et al., 1991 b) encoding bacterial β-galactosidase (β-gal). Two protocols were used to infect the cardiogenic cells. (1) Small blocks (∼50 μm2) of anterolateral mesoderm were dissected from gastrula-stage embryos (stages 4-6) and incubated in liquid medium containing the retrovirus. After removal of CXL, the tissues were dispersed into single-cell suspensions and pressure injected into the precardiac areas of recipient embryos (stages 4-6). Such embryos were then incubated in vitro at 37°C for 2 days (New, 1968), and those embryos with beating hearts were fixed for X-gal histochemistry and paraffin serial sectioning. (2) CXL was pressure injected in ovo (embryonic stages 4-15) into cardiogenic tissues and the eggs subsequently returned to an incubator. At selected stages of development embryos or whole hearts were fixed, stained with X-gal, and serially sectioned after paraffin embedding. The first method showed that (1) cells of the precardiac mesoderm could be infected with the retrovirus, (2) the transplanted cells would differentiate into beating myocytes, and (3) β-gal expression was sufficiently high to be detected histochemically. With the second procedure we could show that (1) β-gal-tagged cells formed colonies in the myocardium, (2) the labeled cells were exclusively myocytes, (3) the number of cells per colony increased with increasing age of embryonic development, (4) the size of colonies was larger in the left than the right ventricle, (5) many of the colonies were transmural, i.e., they extended from epicardial to endocardial layers of the myocardium and generally exhibited a cone or funnel-shape with the base of the cone nearest the epicardium, (6) the orientation of myocytes within each colony changed at different layers of the myocardium, and (7) the cones contained both β-gal+ and β-gal- myocytes. DNA labeling studies with [3H]thymidine indicated that cardiogenic cells divided every 16-18 hr during the first week of development and that the CXL-labeled cells divided indistinguishably from unlabeled myocytes. Based on these observations a model for the growth of the myocardium is presented.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aja.1001930104
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
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