Sex Reversal in Amblystoma. VI. Interactions of Ovary and Testis in Arkansas Strain of Amblystoma Punctatum. ∗

Abstract

In experiments in which one gonadic preprimordium of an embryo was replaced by that of another, it was found that in the local (Buffalo, N. Y.) strain of A. punctatum an ovary developing in the presence of a testis was commonly modified under its influence and eventually reduced to the so-called freemartin condition. 1 In such an ovary the formation of the ovarial sacs (central cavity) is suppressed and the growth of the cortex is inhibited; the gonad is thus eventually reduced to a rudimentary or atrophic structure in which only a few ögonia remain. A comparable modification of the ovaries has been induced in females of this strain joined in parabiosis with males. 2

In the experiment here reported, transplants of the gonadic preprimordium were made in embryos of this same species but of a local race or strain secured from Arkansas. In this strain the ovaries of ungrafted females were found to develop normally, while the gonads of the males commonly exhibited a more pronounced bisexual or hermaphroditic condition than is usually encountered in males of this species. In many cases the gonad had the structure of a testis in its caudal portion, with its cephalic end tending to resemble an ovary (Figs. 1 and 2), but in even more cases the bisexuality consisted rather in a pronounced development of the covering germinal epithelium to give a prominent ‘male cortex’ over a large part of the length of the gonad (Fig. 3). In males under 4 months of age this cortex was sometimes found to be hypertrophied, with many of its germ cells in the spireme stages characteristic of early öcytes; in such gonads the medullary or testicular portion was either poorly developed or possessed cavities of greater or less extent (comparable to those of ovarial sacs) in which numerous spermatogonia lay free, often in some phase of degeneration (Fig. 4).