Abstract
Geinitz 1 showed that, if the dorsal lip of the blastopore is transplanted from an anuran gastrula to the gastrocoel of a urodele, it not only differentiates into typical axial organs but also induces the formation of a neural tube and somites in the urodele tissue with which it is in contact. Lewis 2 attempted to obtain lens induction by implanting an anuran optic vesicle beneath epidermis in the region between the eye and the ear of an Amblystoma embryo but he himself was not sure of the source of the lenses which developed after this operation. Since Geinitz's demonstration of xenoplastic induction, renewed attempts have been made to show that lens formation can be induced by xenoplastically transplanted optic vesicles. Cotronei and Spirito 3 and Mangold 4 have performed experiments bearing on this subject but have not obtained positive results in the species which they used.
In the experiments here reported, Rana palustris and Amblystoma punctatum were used as donor and host respectively. The operation involved removing epidermis from over the left optic vesicle of the urodele host at stage 22-23 and substituting for it a piece of head epidermis from the anuran donor. The donor, which was at approximately the same stage of development as the host at the time of operation, was, however, considerably smaller than the host. Therefore, in order to cover the host's optic vesicle, it was necessary to transplant an extensive piece of the donor's head epidermis.
Animals which had been operated upon were preserved at various stages during embryonal and early larval life, i. e., from 4 to 23 days after operation, and were subsequently examined histologically. Xenoplastic lens induction was found to have taken place in 11 cases.
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