Myogenic cell movement in the developing avian limb bud in presence and absence of the apical ectodermal ridge (AER)

Development ◽  
1984 ◽  
Vol 80 (1) ◽  
pp. 105-125
Author(s):  
Madeleine Gumpel-Pinot ◽  
D. A. Ede ◽  
O. P. Flint

Fragments of quail wing bud containing myogenic cells of somitic origin and fragments of quail sphlanchopleural tissue were introduced into the interior of the wing bud of fowl embryo hosts. No movement of graft into host tissue occurred in the control, but myogenic cells from the quail wing bud fragments underwent long migrations in an apical direction to become incorporated in the developing musculature of the host. When the apical ectodermal ridge (AER), together with some subridge mesenchyme, was removed at the time of grafting, no such cell migration occurred. The capacity of grafted myogenic cells to migrate in the presence of AER persists to H.H. stage 25, when myogenesis has begun, but premyogenic cells in the somites, which normally migrate out into the early limb bud, do not migrate when somite fragments are grafted into the wing bud. Coelomic grafts of apical and proximal wing fragments showed that apical sections of quail wing buds become invaded by myogenic cells of the host, but grafts from proximal wing bud regions do not.

Development ◽  
1977 ◽  
Vol 40 (1) ◽  
pp. 1-21
Author(s):  
Dennis Summerbell

Removal of the apical ectodermal ridge causes a reduction in the rate of outgrowth of the wing-bud and the loss of distal parts. More specifically it causes a short-term increase in cell density and cell death and a decrease in the rate of cell proliferation. The evidence supports the hypothesis of density-dependent control of cell division and suggests that there may also be a mechanism regulating skeletal length at the time of differentiation. An informal model is presented to explain the observations.


Development ◽  
1996 ◽  
Vol 122 (5) ◽  
pp. 1385-1394 ◽  
Author(s):  
J.A. Helms ◽  
C.H. Kim ◽  
G. Eichele ◽  
C. Thaller

In the chick limb bud, the zone of polarizing activity controls limb patterning along the anteroposterior and proximodistal axes. Since retinoic acid can induce ectopic polarizing activity, we examined whether this molecule plays a role in the establishment of the endogenous zone of polarizing activity. Grafts of wing bud mesenchyme treated with physiologic doses of retinoic acid had weak polarizing activity but inclusion of a retinoic acid-exposed apical ectodermal ridge or of prospective wing bud ectoderm evoked strong polarizing activity. Likewise, polarizing activity of prospective wing mesenchyme was markedly enhanced by co-grafting either a retinoic acid-exposed apical ectodermal ridge or ectoderm from the wing region. This equivalence of ectoderm-mesenchyme interactions required for the establishment of polarizing activity in retinoic acid-treated wing buds and in prospective wing tissue, suggests a role of retinoic acid in the establishment of the zone of polarizing activity. We found that prospective wing bud tissue is a high-point of retinoic acid synthesis. Furthermore, retinoid receptor-specific antagonists blocked limb morphogenesis and down-regulated a polarizing signal, sonic hedgehog. Limb agenesis was reversed when antagonist-exposed wing buds were treated with retinoic acid. Our results demonstrate a role of retinoic acid in the establishment of the endogenous zone of polarizing activity.


1989 ◽  
Vol 180 (6) ◽  
pp. 555-566 ◽  
Author(s):  
B. Brand-Saberi ◽  
V. Krenn ◽  
B. Christ

Development ◽  
1979 ◽  
Vol 50 (1) ◽  
pp. 75-97
Author(s):  
Robert A. Kosher ◽  
Mary P. Savage ◽  
Sai-Chung Chan

It has been suggested that one of the major functions of the apical ectodermal ridge (AER) of the embryonic chick limb-bud is to maintain mesenchymal cells directly subjacent to it (i.e. cells extending 00·4–00·5 mm from the AER) in a labile, undifferentiated condition. We have attempted to directly test this hypothesis by subjecting the undifferentiated subridgemesoderm of stage-25 embryonic chick wing-buds to organ culture in the presence and absence of the AER and the ectoderm that normally surrounds the mesoderm dorsally and ventrally. During the period of culture, control explants comprised of the subridge mesoderm capped by the AER and surrounded by the dorsal/ventral ectoderm undergo progressivemorphogenesis characterized by polarized proximal to distal outgrowth and changes in the contour of the developing explant, and ultimately form a structure grossly resembling a normal distal wing-bud tip. In contrast, explants from which the AER and dorsal/ventral ectoderm have been removed (minus ectoderm explants) or from which just the AER has been removed (minus AER explants) form compact, rounded masses exhibiting no signs of morphogenesis. During the polarized proximal to distal outgrowth control explants undergo during the first 3 days of culture, as cells of the explant become located greater than 0·4– 0·5 mm from the AER, they concomitantly undergo a sequence of changes indicative of their differentiation into cartilage. However, those cells which remain 0·4–0·5 mm from the AER during this period retain the characteristics of non-specialized mesenchymal cells. In marked contrast to control explants, virtually all of the cells of minus ectoderm explants initiate chondrogenic differentiation during the first day of culture. Cells comprising the central core of minus AER explants also initiate chondrogenic differentiation during the first day of culture, but in contrast to minus ectoderm explants, non-chondrogenic tissue types form along the periphery of the explants subjacent to the dorsal/ventral ectoderm. These results indicate that the AER maintains cells directly subjacent to it in a labile, undifferentiated condition, and that when mesenchymal cells are freed from the AER's influence either artificially or as a result of normal polarized outgrowth, they are freed to commence cytodifferentiation. The results further suggest that the dorsal/ventral ectoderm may have an influence on the differentiation of the mesenchymal cells directly subjacent to it, once the cells have been removed from the influence of the AER.


Development ◽  
1995 ◽  
Vol 121 (3) ◽  
pp. 661-669 ◽  
Author(s):  
K. Hayashi ◽  
E. Ozawa

It is known that myogenic cells in limb buds are derived from somites. In order to examine the potential of the limb primordium (presumptive limb somatopleure) to induce myogenic cell migration, we transplanted chick presumptive limb somatopleure to the flank region of an embryo, a region that does not normally contribute myogenic cells to the limb. Somitic cell migration was examined using a vital labeling technique. When the presumptive limb somatopleure was transplanted and was in contact with the host flank somite, somitic-cell migration toward the graft was observed. The labeled somitic cells within the graft were identified as myogenic cells in two ways: first, we found that N-cadherin-expressing cells appeared in the graft. Second, after 3 further days of incubation, the somitic cells formed dorsal and ventral masses and expressed sarcomeric myosin heavy chain within the graft. Cell migration occurred only when the somite was in contact with the medial region of the presumptive limb somatopleure. When the somite was not in contact with the limb somatopleure, or when the somite was in contact with the lateral region of the limb somatopleure, migration did not occur. These observations indicate that the potential to induce myogenic cell migration is restricted to the medial region of the presumptive limb somatopleure and that tissue contact is required.


1989 ◽  
Vol 180 (3) ◽  
pp. 293-300 ◽  
Author(s):  
K. K. H. Lee ◽  
D. A. Ede
Keyword(s):  
Limb Bud ◽  

Development ◽  
1985 ◽  
Vol 87 (1) ◽  
pp. 163-174
Author(s):  
Lawrence S. Honig ◽  
Dennis Summerbell

Tissue from the posterior margin of the developing limb bud, when grafted to the anterior margin, evokes the formation of a mirror-image limb duplication from the host tissue. We present maps of the spatial and temporal distribution of this signalling activity in the chick wing bud based on a bioassay that provides a quantitative measure of the completeness of the additional structures (the strength of activity index). Activity is first detected prior to the initial appearance of the limb primordium as early as Hamburger & Hamilton stage 14. It reaches a maximum during early outgrowth of the bud at stages 19 to 25. It then declines as the limb starts to differentiate into its final morphological pattern. The design of the experiment provides serendipitous data showing that two operators can consistently perform grafts with high reproducibility between them while variability between embryos is somewhat higher. The maps of activity are of particular practical value in precisely defining for the experimental embryologist and molecular biologist those positions and stages at which peak signalling activity resides.


Development ◽  
1988 ◽  
Vol 104 (3) ◽  
pp. 361-367 ◽  
Author(s):  
J.L. Carrington ◽  
J.F. Fallon

Outgrowth of normal chick limb bud mesoderm is dependent on the presence of a specialized epithelium called the apical ectodermal ridge. This ectodermal ridge is induced by the mesoderm at about the time of limb bud formation. The limbless mutation in the chick affects apical ectodermal ridge formation in the limb buds of homozygotes. The initial formation of the limb bud appears to be unaffected by the mutation but no ridge develops and further outgrowth, which is normally dependent on the ridge, does not take place. As a result, limbless chicks develop without limbs. In the present study, which utilized a pre-limb-bud recombinant technique, limbless mesoderm induced an apical ectodermal ridge in grafted normal flank ectoderm. However, at stages when normal flank ectoderm is capable of responding to ridge induction, limbless flank ectoderm did not form a ridge or promote outgrowth of a limb in response to normal presumptive wing bud mesoderm. We conclude from this that the limbless mutation affects the ability of the ectoderm to form a ridge. In addition, because the limbless ectoderm has no morphological ridge and no apparent ridge activity (i.e. it does not stabilize limb elements in stage-18 limb bud mesoderm), the limbless mutant demonstrates that the initial formation of the limb bud is independent of apical ectodermal ridge activity.


1978 ◽  
Vol 31 (1) ◽  
pp. 293-322
Author(s):  
C. Tickle ◽  
A. Crawley ◽  
M. Goodman

A survey of the behaviour of a variety of normal and malignant tumours and cells has been carried out to gain insights into the mechanisms of tumour invasiveness. The tumours and cells were implanted into the developing chick wing bud, which is a loose mesenchyme bounded by ectoderm. The distribution of the grafted cells was examined histologically after one or two days. The special feature of this assay is that the behaviour of cells is tested in a 3-dimensional tissue. Cells from 3 different carcinomas, mouse lung tumour, rat bladder tumour and human breast tumour did not invade the mesenchyme, whereas trophoblast, sarcoma 180, cultured hamster fibroblasts (BHK, PyBHK, Nil 8, HSV Nil 8) and neuroblastoma cells did. Cells from embryonic pigmented retina and heart ventricle were non-invasive. These results suggest that cell movement may not be a common feature of all invasive tumours. The cells that did move into the mesenchyme appeared to do so by various mechanisms. Lack of contact inhibition of movement, although probably involved in the invasiveness of sarcoma 180 cells, does not appear to be necessary for invasion: cells that have been shown to exhibit contact inhibition of movement (BHK and PyBHK) also invade. Both normal and transformed cells (BHK and PyBHK; Nil 8 and HSV Nil 8) moved into the mesenchyme. Other invading cells, such as trophoblast, neuroblastoma and to a small extent, HSV Nil 8 cells, destroy the adjacent host tissue and this may be important in the invasiveness of these cells. The patterns of invasion and interactions with the host tissue were varied. Trophoblast and the fibroblasts were often elongated along the basement membrane at the ectoderm/mesenchyme border and also closely apposed to the endothelial linings of blood vessels. Sarcoma 180 and neuroblastoma cells clustered around nerves. The embryonic tissues and neuroblastoma cells were often associated with blood vessels. These results are discussed in relation to tumour invasion. A striking finding was that the carcinoma cells were frequently found positioned within the wing ectoderm on the basement membrane. This affinity of carcinoma cells for the epithelium rather than the mesenchyme leads to a reappraisal of the mechanisms involved in the invasiveness of carcinomas.


Sign in / Sign up

Export Citation Format

Share Document