110 INDUCED BREEDING 



DISCUSSION : 



While the relationship of the anterior pituitary hormone to sexual activity haa heen 

 8\;ispected and then demonstrated for many years, it was In 1929 that Wolf in Wisconsin and 

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

 An5)hlbia could he induced to ov-ulate by means of anterior pltultaiy Implantations. There- 

 after many investigators, Inspired by the urgent need for more embryologlcal material, have 

 described successfully induced ovulations in a wide variety of forms. 



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

 amphibia, and the amphibian pltultaiy hormone can Induce heightened sex activity and hyper- 

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

 species specificity In the gonadotropic activity of the anterior pltuii-ary 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 pltuitarlea, 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 

 pitultaries from fish, reptiles, birds, and mammals. That the reverse has not been equal- 

 ly 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 

 mammalian extracts may be due to toxic reactions to the extractants, or to some very spe- 

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



It has not yet been determined Just how the axiterior 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 an^hibla so that eggs and embryos of 

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



BJ!H''i!J<ENCES : 



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