INDUCED BREEDING 101 



DISCUSSION: 



While the relationship of the anterior pituitary hormone to sexual activity has been sus- 

 pected and then demonstrated for many years, it was in 1929 that Wolf in Wisconsin and 

 Houssay in Brazil almost simultaneously published results of their observations that the 

 Amphibia could be induced to ovulate by means of anterior pituitary implantations. There- 

 after many investigators, inspired by the urgent need for more embryological material, 

 have described successfully induced ovulations in a wide variety of forms. 



Since the nnammalian pituitary hormone can induce sexual activity and ovulation in some 

 amphibia, and the amphibian pituitary hormone can induce heightened sex activity and hy- 

 pertrophy of the reproductive organs in mammals, it is no longer tenable that there is any 

 species specificity in the gonadotropic activity of the anterior pituitary gland hormones. 

 It is true that frogs have thus far proven to be negative to the mammalian extracts, but 

 toads are most responsive to these same hormones. It is true that ovulation in mammals 

 has not been induced, even with large doses of Anuran pituitaries, although the genital 

 system has responded, indicating that there may be a great difference in threshold and in 

 the quantitative value of the glands. Nevertheless, there is evidence that there is present 

 a gonadotropic hormone which will stimulate sexual activity in the amphibia in the pitu- 

 itaries from fish, reptiles, birds, and mammals. That the reverse has not been equally 

 demonstrated may be only an indication that the gland attains greater gonadotropic potency 

 with the ascendency in the evolutionary scale. The negative reactions of frogs to mam- 

 malian extracts may be due to toxic reactions to the extractants, or to some very specific 

 protein sensitivity. No doubt this exception will eventually be explained. 



It has not yet been determined just how the anterior pituitary hormone acts to induce 

 ovulation in the Amphibia. Attempts have been made to eliminate the circulatory and/or 

 the nervous connections. Once the pathway of action is determined it may be possible to 

 explain certain individual or species variations that have thus far eluded investigation. 



CONCLUSIONS: 



It is now possible to induce ovulation among the amphibia so that eggs and embryos of 

 the various species are available at all seasons of the year. 



REFERENCES 



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 AD.'\MS, A. E. G B. GRANGER, 1938 - "Induction of ovulation in Rana pipiens by pituitaries of Triturus viridescens. " Proc. 



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 ALEXANDER, S. S. G C. W. BELLERBY, 1938 - "Experimental studies on the sexual cycle of the South African clawed toad 



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