Abstract
When the otic plate is exchanged between early embryos of Amblystoma punctatum and A. tigrinum, the results agree essentially with similar transplantations of the limb, eye, and nasal placode, but are modified due to the location of the ear in the head. (Harrison, 1 Twitty, 2 , 3 Schwind, 3 Stone, 4 Burr. 5 )
The grafted auditory vesicle develops normally and becomes functional in both species, judging by the equilibratory reactions. The relative size of the normal and transplanted ears was estimated by weighing paper models of the labyrinth. The weights indicate that the tigrinum graft on the punctatum host, though larger than the normal punctatum ear, becomes greatly retarded in its growth, as compared with its own species control, while the punctatum ear on tigrinum, though smaller than the normal tigrinum, exceeds the normal punctatum ear in size.
The cartilaginous capsule, measured in the same way, shows some response to the presence of the transplant, but the capsule around the tigrinum graft is proportionately smaller than that surrounding the normal tigrinum ear. Conversely, the capsule around the punctatum graft on tigrinum is larger than the normal capsule in the punctatum donor. This may possibly be due to a difference in the amount of cartilage-forming material available in the 2 species. None of the other adjacent cartilages is affected, with the exception of the columella, which shows corresponding deviations in size.
Models of the muscles which originate on the ear capsule demonstrate no growth responses, but their position on the larger or smaller capsules is shifted. In Twitty's study of the eye muscles after heteroplastic transplantation of the eye, hypertrophy or atrophy was marked.
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