Abstract
The writer 1 and Burns, 2 using different technical methods, have demonstrated that the testis (or potential testis) of A. punctatum (maculatum) may undergo reversal or transformation to an ovary when kept throughout development under the influence of a female of the more rapidly developing species, A. tigrinum. The structural changes involved in this reversal have been described. 1 , 2 The present report offers further evidence of the occurrence of such reversal of testis to ovary.
Right gonadic preprimordia of A. mexicanum (Mexican axolotl) embryos were removed and replaced by the corresponding preprimordia of A. punctatum donors. All operations were performed during tail-bud stages (28 to 32 of Harrison's series), employing the technique previously described. 3 Embryos serving as donors were reared whenever possible as a check upon the sex type of the gonad derived from the transplant. This gonad has been studied in serial sections in the case of hosts dying or killed during earlier stages, or its type has been ascertained by exploratory operation in the case of hosts surviving to more advanced ages (4 months or over). The sex of the host has been ascertained by similar study of its remaining gonad (on left side).
In the 37 hosts found to be females, the gonad derived from the transplant proved to be a testis in only 2 cases (5.4%) instead of the 50% expected on the basis of the approximately 1:1 sex ratio exhibited by the donor species. Of the donors furnishing transplants for these 37 hosts, 28 survived—16 females and 12 males. There are thus 10 cases in which the gonad of the transplant, although an ovary, is known to have been derived from a gonadic preprimordium supplied by a male donor.
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