Effect of retinoic acid onFgf‐8expression in regenerating urodele amphibian limbs

Abstract

In our previous study, we have shown that Fgf‐8 is expressed in the basal layer of the apical epithelial cap (AEC) and in the underlying thin layer of mesenchymal tissue of the regenerating limbs of Mexican axolotl, Amby‐stoma mexicanum. Our present RT‐PCR data also demonstrate that Fgf‐8 transcript is localized both in the mesenchymal and epidermal tissues. To understand the effect of retinoic acid (RA) on the expression of Fgf‐8 in the regenerating axolotl limbs, RA was injected intraperitoneally at the dediffer‐entiation stage of limb regeneration. The RA treatment caused a change in the Fgf‐8 expression profile of the regenerating limbs. In RA‐treated limbs, duration of Fgf‐8 expression was prolonged and a high level of expression was maintained during dedifferentiation and blastema formation stages. These results suggest that Fgf‐8 is an important molecule in the process of pattern duplication of regenerating salamander limbs evoked by RA treatment.