THE PITUITARY BODY 



quently by gonadotropic extracts other than those of the an- 

 terior lobe. No accurate quantitative studies by this method 

 have been made. 



3. The production of ovulation in the adult rabbit in oestrus. 

 — A sensitive and accurate**^ method of determining the 

 amount of a gonadotropic hormone is by the production of 



Fig. 23- — The relationship between the dose of an extract of the pars glandu- 

 laris and ovulation in the rabbit. Each point represents a group of twenty or more 

 rabbits. The percentage of animals in which ovulation was observed is indicated 

 along the ordinate. From Hill, Parkes, and White (1934). 



ovulation in the adult rabbit in oestrus. The presence of oes- 

 trus is important because the ovaries then contain large or 

 ripe follicles. The only adequate quantitative study of the 

 relationship between the dose and the response is that of Hill, 

 Parkes, and White (1934). They concluded that there is a 

 satisfactory relationship between the dose of gonadotropic 

 hormone and the percentage of rabbits ovulating (see Fig. 

 23). In other studies in which prolan was used, they pointed 



^•5 Provided that a large enough group of rabbits (20-30) is given each dose. 

 [170] 



