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Leg development in a frog without a tadpole (Eleutherodactylus coqui)
1Department of Zoology, University of Toronto, Ontario, Canada.
The Journal of Experimental Zoology
|October 1, 1994
Summary
Direct developing frogs, Eleutherodactylus coqui, lack a tadpole stage. Their limb buds require a specific embryonic factor for full leg development, as shown by in vitro and cross-species transplantation experiments.
Area of Science:
- Developmental biology
- Amphibian embryology
- Comparative anatomy
Background:
- Direct developing frogs, such as Eleutherodactylus coqui, bypass the tadpole stage.
- Limb bud development in these frogs is continuous throughout embryonic life.
Purpose of the Study:
- To investigate the autonomous development capacity of Eleutherodactylus coqui limb buds.
- To identify factors influencing limb growth in direct developing frogs.
Main Methods:
- Explantation of limb buds in vitro.
- Transplantation of limb buds to Rana pipiens embryos.
- Transplantation of limb buds to different sites on Eleutherodactylus coqui embryos.
Main Results:
- In vitro cultured limb buds showed limited development and then arrested.
- Transplanted limb buds to Rana pipiens formed legs with digits and cartilage but no elongation.
- Limb buds transplanted within Eleutherodactylus coqui embryos developed more completely.
Conclusions:
- A systemic factor present in Eleutherodactylus coqui embryos is crucial for continuous leg growth.
- This factor is necessary for full limb development, beyond what is observed in vitro or in heterospecific transplants.
- Thyroid hormone's role in this process has not yet been confirmed.