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Journal of Experimental Biology 14,1-15 (1937)
Published by Company of Biologists 1937

Studies on Amphibian Metamorphosis : XV. Direct Tympanic Membrane Formation from Dermal Plicae Integument Transplanted to the Ear Region

O. M. HELFF ¹

¹ Department of Biology, University College, New York University

The writer has previously shown that fully developed anuran dermal plicae undergo complete regression following heteroplastic transplantation to the larva. Subsequent retransplantation to the ear region of metamorphosing larvae results in the development of normal tympanic membranes. Whether such transformation will occur following direct transplantation of dermal plicae to the ear region was tested in the present work by the following operations:

Autoplastic R. clamitans and R. palustris transplantations resulted, in general, in little or no regression of dermal plicae.

Homoplastic transplantations resulted in complete regression in R. clamitans and partial regression in R. palustris. In the former species, partial, and in the latter, no tympanic membrane development occurred.

Heteroplastic transplantations from R. clamitans to R. palustris and R. catesbeiana resulted in complete regression in both cases, with the development of well-formed tympanic membranes.

Heteroplastic transplantations from R. palustris resulted in partial regression on R. clamitans hosts and usually no tympanic membrane development. Transplants on R. catesbeiana hosts underwent complete regression and tympanic membrane formation.

The conclusions are reached that autoplastic transplantations usually do not result in dermal plicae regression; homoplastic transplantations result in partial to complete regression but without tympanic membrane formation; while heteroplastic transplantations usually involve complete regression and full tympanic membrane development.

Initial heteroplastic transplantation to larval hosts is thus not essential, in that direct heteroplastic transplantation from young frogs to the ear region of metamorphosing larvae will result in total regression of dermal plicae structure and complete membrane formation.