Abstract
The formation of the tympanic membrane constitutes one of the last adult structures to be developed during the metamorphosis of the frog tadpole. The present communication, based on over 300 autoplastic transplantations, is designed to point out the factors responsible for its formation.
Histological sections of tympanic membranes in various stages of development show clearly that a definite series of events takes place in the integument during which the stratum spongiosum and stratum compactum layers disappear and the latter is replaced with a network of fibrous elements typical of the adult tympanic membrane.
Preliminary transplantations of skin grafts from the back and side of the tadpole to the tympanic membrane region, resulted in the formation of typical membranes in the grafts during metamorphosis. This would indicate that all integument of the metamorphosing tadpole is totipotent in this regard and that structures in the immediate vicinity of the tympanic membrane region have a direct influence on membrane formation.
Autoplastic transplantations of the annular tympanic cartilage in various stages of development were made to regions under the skin of the side and under the skin of the back of metamorphosing tadpoles. Typical tympanic membranes were formed in the skin of the back directly over the annular tympanic cartilage transplants. Less perfectly formed membranes developed in the skin of the side directly over the transplants. Histological sections of such membranes showed that typical cellular transformations had taken place, identical to those found in normal membrane formation.
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