LEG DEVELOPMENT IN A FROG WITHOUT A TADPOLE (ELEUTHERODACTYLUS-COQUI)

Direct developing frogs, like Eleutherodactylus coqui, have deleted th e tadpole from their life history. Limb buds appear early and develop continuously through embryonic life. The capacity for autonomous devel opment of E. coqui limb buds was tested by explantation and transplant ation. When limb buds were explanted to in vitro culture, they progres sed for a few stages and then arrested. When limb buds were transplant ed to embryos of a typical tadpole species (Rana pipiens), the buds fo rmed legs with knees, digits, and some cartilage, but they did not elo ngate. Since limb buds transplanted to various sites on E. coqui embry os tended to develop completely, the limited development of the explan ts in vitro and the transplants to R. pipiens suggests the presence of a systemic factor in the embryo involved in the normal continuous gro wth of E. coqui legs. Attempts to demonstrate a role for thyroid hormo ne have thus far been unsuccessful. (C) 1994 Wiley-Liss, Inc.