THE PITUITARY BODY 



that this substance (or substances) is secreted by the pars 

 glandularis of the pituitary and that it (or they) is what today 

 is called the gonadotropic hormone (or hormones). It is gen- 

 erally agreed that gonadotropic hormones directly affect only 

 the primary sex organs (ovaries and testes). Other effects on 

 the generative tract (uterus, vagina, seminal vesicles, pros- 

 tate, etc.) depend upon the stimulation of the primary sex 

 organs and, therefore, cannot be produced in gonadectomized 

 animals. 



Despite the publication of a tremendous number of papers 

 dealing in whole or in part with gonadotropic substances, 

 many questions of fundamental importance have not been 

 answered satisfactorily. Among significant problems not yet 

 solved are the following: (i) The question of the number of 

 gonadotropic hormones secreted by the pituitary body has 

 been answered in the most varied way. Some investigators 

 postulate only one, others, as many as five. This question 

 will be answered — but perhaps not completely answered — 

 when the various hormones thought to exist will have been 

 isolated as pure substances. (2) How are the gonadotropic 

 hormones, secreted by the pars glandularis, related, if at all, 

 to the gonadotropic substances of the body-fluids of pregnant 

 women and horses, to those of the placenta and mucosa of the 

 pregnant uterus (woman and horse), and to those of malig- 

 nant tumors of the generative tract of men and women ? This 

 problem is discussed in chapter v. (3) The physiology, in- 

 cluding the comparative physiology, of the pituitary-gonad 

 group of glands of internal secretion will still require much 

 investigation, the progress of which partly depends upon the 

 isolation of gonadotropic hormones as pure substances. 

 Many interesting conclusions rest on a flimsy foundation. As 

 matters now stand, almost every investigator uses a different 

 preparation. The evaluation of results may be further com- 

 plicated by the use of different methods of administration 

 and by the use of different animals. Diet, care, and age also 



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