igo Pituitary Gonadotrophins 



literature in which a male and a female rat were subjected to the control of 

 the same pituitary.^ In the female, follicular and uterine stimulation were 

 evident; in the male, testis and accessory-organ growth occurred. Duplication 

 of these conditions and effects by treating males and females wath a known 

 FSH-ICSH mixture has shown that these cannot be interpreted as evidence 

 for the secretion by the pituitary of a single gonadotrophin.^* The observed 

 phenomena are better explained by the fact that, in the female, ICSH aug- 

 ments the action of the FSH while, in the male, only its intrinsic hormono- 

 trophic action becomes evident. 



Conclusions 



An attempt has been made to summarize and coordinate briefly the results 

 of investigations carried out in this and other laboratories within the last few 

 years, concerning pituitary gonadotrophins. While a number of recent find- 

 ings are included in this discussion, the detailed presentation of new data has 

 been avoided. 



The preparation in pure form of one of the gonadotrophins, the interstitial- 

 tissue-stimulating hormone (ICSH), has been described. Great differences in 

 the physicochemical properties of pure ICSH obtained from sheep and hog 

 pituitaries have been demonstrated. Nevertheless the biological activity of 

 the two compounds was found to be similar, both qualitatively and quanti- 

 tatively. Similar though less pronounced chemical species differences have 

 been noted also for sheep and beef lactogenic hormones. Species differences 

 have thus become a factor to be reckoned with when comparing the properties 

 of hormones obtained from different animal species. Biological differences be- 

 tween follicle-stimulating hormones (FSH) from sheep and hog pituitaries 

 may rest on chemical differences between hormones of the two sources. 



Besides these species differences, there are already well-established contrasts 

 between gonadotrophins from the pituitary and those of chorionic (or endo- 

 metrial) origin. It appears possible that the hormones secreted by the pituitary 

 resemble more those of placental origin than those extracted from the gland. 

 However, the small amounts of pituitary hormones circulating in the blood 

 makes their purification as yet impracticable, and gland extracts have there- 

 fore been generally used as source material for the isolation of hormones. The 

 biological properties of FSH and ICSH prepared in this manner have been 

 summarized. The intrinsic effects of ICSH which characterize it as a separate 

 hormone have been considered separately from those "augmentation" effects 

 which are evident only in the presence of FSH and may be simulated by non- 

 specific agents which act merely by delaying the absorption of FSH. 



