104 



BIOLOGIC BASIS OF SEX 



Testes develop normally except that in cas- 

 trate hosts there is some hypertrophy of the 

 interstitial tissue, presumably in response 

 to the gonaclotrophin of the host (a phe- 

 nomenon also reported by Jost, 1948b I. 

 Again many prospective ovaries give rise to 

 gonads in which both cortex and medulla are 

 well differentiated, the hypertrophied med- 

 ullary cords sometimes approaching the 

 structure of testis tubules. Cells resembling 

 the interstitial cells of the testis are also 

 found around these transformed medullary 

 cords in grafts developing in castrate hosts. 

 On the whole the ovarial cortex is better 

 developed than in the experiments of Buyse, 

 because perhaps the gonads were usually 

 older and better differentiated at the time 

 of transplantation. 



Similar forms of develojiment are found 

 when embryonic gonads are transplanted to 

 the omentum of adult hosts (Holyoke, 

 1949). Testes develop in a virtually normal 

 manner regardless of the sex of the host; 

 this author, however, describes certain ef- 

 fects which appear relatively late, after the 

 testis has acquired its characteristic tubular 

 structure. These are: (1) repression of tu- 

 bule growth in some cases, with degenera- 

 tive changes, a condition which was ob- 

 served only in grafts growing in female 

 hosts; (2) an increase in the amount of in- 

 terstitium present, similar apparently to 

 that reported by Moore and Price. Trans- 

 planted ovaries display the same variability 

 as in the foregoing experiments; cortical 

 development is adversely affected and some- 

 times fails altogether. In all cases in which 

 cortical structure could be well identified 

 there was also more or less hypertrophy of 

 the medulla, sometimes to the point where 

 the gonads were classified as ovotestes. This 

 latter condition was reported only in male 

 hosts, and this is perhaps the only change 

 that might be interpreted as a reversal of 

 sex conditioned by the sex of the host. On 

 this point the findings differ from those of 

 Buyse, of Moore and Price, and of Torrey, 

 all of whom reported similar changes but 

 without relation to the host's sex. 



A further study of the problem was made 

 by Torrey (1950). In his experiments the 

 embryonic gonads were transplanted to the 

 anterior chamber of the eye, using hosts of 

 various ages and of both sexes. He con- 



firmed the main conclusions of Buyse and 

 of Moore and Price (Holyoke's study was 

 not then available for consideration), 

 namely, that regardless of the stage at 

 which the primordium is isolated, testes are 

 capable of an autonomous and virtually 

 normal development, irrespective of the type 

 of host in which they develop, whereas 

 ovaries vary greatly in the state of differen- 

 tiation attained, depending on the stage of 

 development at which they are isolated. 



Torrey paid particular attention to the 

 importance of developmental age in the fate 

 of grafted ovaries. When transplanted before 

 the appearance of a definite cortical zone 

 (zone of secondary sex cords), prospective 

 ovaries show little capacity for development 

 of cortex; on the contrary (as found by 

 l^revious workers), there is a marked tend- 

 ency to hypertrophy of the medullary com- 

 ponent, leading in some cases to testis for- 

 mation. This tendency is not influenced by 

 the sex of the host; rather, it seems to be 

 inherent in the state of organization of the 

 primordium at the time of transplantation. 

 In the young ovary the medullary compo- 

 nent (primary sex cords) is already in 

 existence; the cortex does not appear as a 

 discrete tissue until much later, and only 

 after a well defined cortex is present is the 

 gonad capable of development as an ovary. 

 The fate of the transplanted ovary appears, 

 then, to be primarily a iiiatter of the self- 

 differentiating capacities of the elements 

 already formed and present in the primor- 

 dium at the time of its isolation. The de- 

 velopment of these elements is influenced 

 also by the temperature of the eye chamber, 

 a point not directly involved in the present 

 discussion. 



In the foregoing experiments it has been 

 emjihasized that the hormonal environment 

 provided by the host seems to have no im- 

 portant influence on the sexual differentia- 

 tion of the transplanted gonads (for a par- 

 tial exception as noted above see Holyoke) . 

 The question thus arises whether the hor- 

 mones of embryonic gonads might be more 

 effective. An answer to this question was 

 sought by Mclntyre (1956) who trans- 

 planted the eml)ryonic testis and ovary to- 

 gether beneath the capsule of the kidney of 

 adult castrate hosts of both sexes. The gon- 

 ads were ])laccd in close contact in order 



