Gonadokinetic Effects in Parabiotic Rats

Abstract

It has been shown1 that in parabiotic rats the testes of a hypophysectomized partner could be completely maintained in or restored to a normal condition by gonad-stimulating hormone emanating from the pituitary of a castrated twin. It was also reported that the pituitaries of cryptorchid and of normal partners were in this respect much less potent than those of castrates. The data which will be presented in this report for the most part confirm and extend the previous work.As regards the response of the testes of a hypophysectomized parabiotic twin it has been our experience that the following factors are of greatest importance in the final analysis: (1) The type of partner ; whether castrated (regardless of sex), cryptorchid, or normal.(2) The time necessary for adequate vascular anastomosis between the partners. (3) The time necessary for a physiological process to become manifest or to run to completion.Experience has shown that the scrotum in the rat reacts to testicular hormone much as do the accessory sexual organs.'. From the results of our former and present studies in parabiotic rats we have found it possible to conclude that the scrotum in a hypophysectomized parabiotic rat is qualitatively more sensitive to testicular hormone than are the prostate and seminal vesicles. This has proved to be an important criterion in our work on parabiotic rats, as a pair does not have to be sacrificed in order to discover from the condition of the accessory sexual glands and the interstitial cells of the testes whether or not testicular hormone is being produced. Further, our previous observations, confirmed by later results, have shown that within certain limits the size of the testes in a hypophysectomized parabiotic rat is an index to the degree of their gametogenic activity. This is especially true when the testes are large, since the interstitial tissue at best forms but a small fraction of the whole testis. For these reasons, the hypophysectomized

Response of X-Irradiated and Cryptorchid Testes to Endogenous Gonadotrophins in Parabiotic Rats

“…Moore (1944) indicated that the severity of effects depends upon the age at which the testes are made cryptorchid and the length of time they are so maintained. These authors also found, as well as Cutuly & Cutuly (1937), that, similarly, hypophyses of cryptorchid males release increased amounts of gonadotrophin as reflected in gonads and accessory sex organs of intact partners. These authors also found, as well as Cutuly & Cutuly (1937), that, similarly, hypophyses of cryptorchid males release increased amounts of gonadotrophin as reflected in gonads and accessory sex organs of intact partners.…”