title: Proximo-distal pattern regulation in deficient avian limb buds.
abstract: Deficient limb buds composed of prospective stylopod and autopod are able to regulate the missing intercalary zeugopod, the origin of which was investigated by heterospecific quail/chick recombinants. The associations of quail prospective autopod and chick prospective stylopod failed to regulate. The reverse combination of chick prospective autopod grafted onto a quail prospective stylopod gave rise to a three-segmented limb. In 13 out of 16 cases the regulated zeugopod was made up of both chick and quail cells. Chick cells were located predominantly along the postaxial half of the zeugopod, while the quail cells made up most of its preaxial half. In two cases, the intercalary zeugopod consisted exclusively of chick cells originating from the tip and in one case of quail cells originating from the base.These results demonstrate that during the regulative processes, the prospective values of some of the original stylopodial and autopodial cells have been shifted along the proximo-distal axis, towards the expression of more distal as well as of more proximal structures.Heteropolar stylo-autopodial or zeugo-autopodial recombinants, in which the proximo-distal axis of the base was reversed with respect to that of the tip, were unable to regulate the pattern defects and thus revealed the importance of concordant p-d polarity for regulative processes to take place between abutted tissues.
authors.affiliation: Laboratoire de Zoologie et Biologie animale, Equipe de Recherche associée au CNRS no 621, Université scientifique et médicale de Grenoble, Boîte postale no 53-Centre de Tri, F-38041, Grenoble-Cedex, France.
authors.forename: Madeleine
authors.initials: M
authors.lastname: Kieny
authors.affiliation: Laboratoire de Zoologie et Biologie animale, Equipe de Recherche associée au CNRS no 621, Université scientifique et médicale de Grenoble, Boîte postale no 53-Centre de Tri, F-38041, Grenoble-Cedex, France.
authors.forename: Marie-Paule
authors.initials: MP
authors.lastname: Pautou
keywords: Limb but; Proximo-distal polarity; Regulative capacities; Xenoplastic recombinants