Msx1 expressing mesoderm is important for the apical ectodermal ridge (AER)-signal transfer in chick limb development
Version of Record online: 27 OCT 2003
Development, Growth & Differentiation
Volume 39, Issue 6, pages 705–714, December 1997
How to Cite
Hara, K. and Ide, H. (1997), Msx1 expressing mesoderm is important for the apical ectodermal ridge (AER)-signal transfer in chick limb development. Development, Growth & Differentiation, 39: 705–714. doi: 10.1046/j.1440-169X.1997.t01-5-00006.x
- Issue online: 27 OCT 2003
- Version of Record online: 27 OCT 2003
- Received 16 April 1997; revised 19 June 1997; accepted 19 June 1997.
- apical ectodermal ridge;
The apical ectodermal ridge (AER) is a specialized thickening of the distal limb ectoderm, and its signals are known to support limb morphogenesis. The expression of a homeobox gene, Msx1, in the distal limb mesoderm depends on signals from the AER. In the present paper it is reported that Msx1 expression in the distal mesoderm is necessary for the transfer of AER signals in chick limb buds. Interruption of AER-mesoderm interaction by insertion of a thick filter led to the inhibition of pattern specification in the mesoderm just under the filter. In such cases, the expression of Msx1 disappeared in the mesoderm under the filter, suggesting that AER is able to signal over short ranges. In advanced limb buds, Msx1 is also expressed in the proximal mesoderm under the anterior ectoderm. However, it was found that a grafted antero-proximal mesoderm shows no inhibitory effects on pattern specification of the host mesoderm, as is the case with the distal mesoderm. On the other hand, grafted mesoderms without potent Msx1 re-expression, even underneath AER, disturbed normal limb development. In such cases, the expression of Msx1 disappeared in the mesoderm under the grafts, whereas Fgf-8 expression was maintained in the AER above the graft. These results indicate that the expression of Msx1 in the mesoderm is important for the transfer of AER signals.