THE PITUITARY BODY 



fects) of gonadotropic hormone is concerned, the following 

 statements appear to be at least approximately correct. 

 Judged by its ability to produce ovarian changes in immature 

 mice and rats, the pars glandularis of the ox contains the low- 

 est concentration of gonadotropic hormone(s). The concen- 

 tration of the gonadotropic hormone(s) in the pituitary or 

 anterior lobe of other animals appears to vary as follows: 

 horse (especially if castrated) > sheep > pig; rat>rabbit> 

 guinea pig; non-pregnant woman > pregnant woman. An- 

 other type of assay — the production of ovulation in the rab- 

 bit in oestrus — yields different results. According to this test 

 (Hill), the following relationships appear to hold: sheep >or 

 = horse = pig but far > ox. Differences in potency depending 

 upon sex (cat, dog, guinea pig, rabbit, and rat) are considered 

 later." 



The discussion of the comparative physiology of the 

 gonadotropic hormones either as assayed by using the ani- 

 mal's own pituitary or as determined by the response of the 

 animal's gonads will be divided according to the following 

 groups of animals: (i) the ox, sheep, pig, and horse; (2) the 

 mouse, rat, and guinea pig; (3) the rabbit, cat, and ferret 

 (animals which normally ovulate only after coitus); (4) the 

 dog, ground-squirrel, and whale (a miscellaneous group); and 

 (5) the monkey and man. 



I . The ox, sheep, pig, and horse. — In only one animal of this 

 group (the pig) has any attempt been made to study the 

 effect of extracts of the anterior pituitary on the gonads. 



All investigators agree that the concentration of gonado- 

 tropic hormone(s) in the pars glandularis of the ox is very 

 low (typical effects ordinarily are detected only by the most 



" The statements so far made are based on the reports of the following authors: 

 Smith, and Smith and Engle (1927); Lipschiitz and others (1928, 1931-32); Wallen- 

 Lawrence and van Dyke (1931); Philipp 1931); Loeb and others (1932-33); Magis- 

 tris (1932); Severinghaus (1932); D'Amour and van Dyke (1933); Hellbaum (1933); 

 and Hill (1934). The reports of Magistris (1932) and of Hill (1934) deal particularly 

 with this problem. 



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