Abstract
In contrast to the pattern of limb emergence in mammals, chicks, and the
newt N. viridescens, embryos such as Xenopus laevis and Eleutherodactylus
coqui initiate pelvic limb buds before they develop pectoral ones. We
studied the expression of Pitx1 in X. laevis and E. coqui to determine if
this paired-like homeodomain transcription factor directs differentiation
specifically of the hindlimb, or if it directs the second pair of limbs to
form, namely the forelimbs. We also undertook to determine if embryonic
expression patterns were recapitulated during the regeneration of an
amputated limb bud. Pitx1 is expressed in hindlimbs in both X. laevis and
E. coqui, and expression is similar in both developing and regenerating
limb buds. Expression in hindlimbs is restricted to regions of
proliferating mesenchyme.Key words: regeneration, Xenopus laevis, limb
bud, Pitx1 protein, specification. Biochemistry
and Cell Biology, 2006, 84(2): 257-262, 10.1139/o06-036