224 p. N. MARTINOVITCH, D. PAVIC, D. SLADIC-SIMIC AND N. ZIVKOVIC 



It is not our purpose to discuss here modern views on the hypothalamus- 

 anterior pituitary relationship. What we wish to do is to point out some facts 

 that have become evident from our work on the hypophysectomized-grafted 

 rats. One of them is the capacity of the grafts to stimulate the growth of the 

 adrenal glands arrested at hypophysectomy. The other fact is the capacity 

 of the adrenals of such rats to react with a highly significant drop in the 

 concentration of cholesterol mider stress mediated through a whole-body 

 exposure of the host animal to a lethal dose of X-rays. 



The implications of these findmgs, as it appears to us, are quite obvious. It 

 seems that the anterior pituitaries grafted at a site (anterior eye chamber) 

 removed from the hypothalamus will synthesize sufficient amounts of ACTH 

 to stimulate adrenal growth and elicit the classical cholesterol reaction in the 

 gland when a whole-body lethal dose of X-rays is appHed as the stressor. 



Under the assumption that the dependence of the anterior pituitary on 

 the hypothalamus for its functional activity is an established fact we thought 

 it worthy of effort to see if this dependence finds its expression in situations 

 where the anterior pituitaries are grafted into positions removed from the 

 hypothalamus (heterotopic grafting). The next logical step, therefore, involved 

 a search for the region in the hypothalamus responsible for the activation of 

 the pituitary gland. The electro-coagulation technique, widely applied in the 

 study of the specific activity of the various areas of the brain mass, we hoped 

 might give an answer to this question, and the median eminence was 

 selected as the region to be destroyed. Three months following the destruction 

 of the median eminence the rats were exposed to a lethal dose of X-rays. The 

 results obtamed are given in Table IV. 



Before offering these results for discussion we should like to call attention 

 to the fact that the number of animals upon which a discussion can be based 

 is rather small. Unfortunately, a number of animals succumbed to the median 

 eminence destruction operation. In some other rats in vivo we failed to find 

 the adrenal gland owing to the presence of a heavy mass of fatty tissue in the 

 region of the kidney.| The number of animals from which one gland had been 

 removed before the destruction of the median eminence and the other 3 hours 

 after exposure to X-rays was reduced to 6. Four out of these 6 animals after 

 irradiation showed a distinct drop in cholesterol concentration in the remain- 

 ing gland; two did not. The adrenal gland of one of the latter animals weighed 

 somewhat less than the gland extirpated months earlier, which is not usual. 

 To draw conclusions from 6 animals on the role played by the median 

 eminence region in the processes that control the synthesis and release of 

 ACTH by the anterior pituitary after transplantation into the anterior 

 chamber of the eye would not be a right thing to do. If, however, cholesterol 



t For the cholesterol concentration test one adrenal was removed on the day of operation 

 upon the median eminence, and the other 3 months later. 



