title: Opercular development and ontogenetic re-organization in a direct-developing frog.
abstract: The direct-developing frog, Eleutherodactylus coqui, has eliminated the tadpole stage from its ontogeny, and lacks many larval characters. We demonstrate that the dermal folds of E. coqui are homologous with the opercular folds of metamorphosing frogs. In both E. coqui and its metamorphic counterparts the opercular folds grow over the developing forelimb before perforating to free the entrapped limb. Opercular perforation in E. coqui occurs even in the absence of the forelimb but shows no signs of thyroid hormone dependence. The condensation of E. coqui development appears due to the excision of the extended larval period of developmental stasis. Analysis of opercular development, when viewed in conjunction with other developmental characters, suggests the ontogenetic period in the ancestral Eleutherodactylus life-history from which the tadpole was likely eliminated.
authors.affiliation: Department of Anatomy and Cell Biology, University of Toronto, Toronto, Ontario, M5S 1A8, Canada.
authors.forename: E M
authors.initials: EM
authors.lastname: Callery
authors.forename: R P
authors.initials: RP
authors.lastname: Elinson
mesh_terms: D000818:Animals; D001001:Anura / Q000196:embryology*; D005075:Biological Evolution; D019521:Body Patterning / Q000187:drug effects; D020405:Dermis / Q000187:drug effects / Q000196:embryology*; D005121:Extremities / Q000196:embryology; D007814:Larva / Q000187:drug effects / Q000254:growth & development; D018878:Limb Buds / Q000187:drug effects / Q000196:embryology; D008675:Metamorphosis, Biological / Q000187:drug effects; D009024:Morphogenesis / Q000187:drug effects; D013963:Thyroid Hormones / Q000494:pharmacology
chemical_list: D013963:Thyroid Hormones