THE PITUITARY BODY 



SUMMARY 



Anterior pituitary secretion is a necessary condition of nor- 

 mal function of the gonads of all classes of vertebrates. How 

 this necessary condition is implemented in the living animal 

 has been of prime interest to a host of biological investigators, 

 both seasoned and newly recruited. Although experiments 

 have been performed in all classes of vertebrates — fishes, 

 amphibia, reptiles, birds, and mammals — there still remain 

 lamentably great gaps in our knowledge of the physiology of 

 gonadotropic hormones. It is an unenviable task to sum- 

 marize the work, because unifying working concepts either 

 are lacking or may be widely used without equally wide 

 recognition of their inadequate experimental foundations. 



Discussion is difficult if there is not agreement on the prob- 

 able number of gonadotropic hormones. Yet no investigator 

 has succeeded in preparing a gonadotropic hormone in pure 

 form. Partial purification has apparently been achieved and 

 there continues to be evidence that there are two gonado- 

 tropic hormones: one facilitating follicle-growth and matura- 

 tion (follicle-stimulating hormone), the other promoting the 

 conversion of the cells of the membrana granulosa and thecae 

 into lutein cells (luteinizing hormone). Both hormones are 

 said to be necessary to produce ovulation. There is evidence 

 that what is called follicle-stimulating hormone maintains 

 spermatogenesis in the testis, whereas luteinizing hormone 

 nurtures the interstitial cells of Leydig, whence arises "male 

 hormone."'^ Some authors would lengthen the list further 



"' However, other data suggest different interpretations. Observations which 

 must be reconciled are as follows: (i) follicle-stimulating hormone maintains the 

 germinal epithelium, whereas the interstitial cells require luteinizing hormone for 

 normal function (immature hypophysectomized male rats); (2) either hormone will 

 support spermatogenesis, but only luteinizing hormone maintains the interstitial 

 cells (mature hypophysectomized male rats); (3) spermatogenesis can take place 

 normally in the absence of the pituitary, provided that a suitable androgen ("male 

 hormone") is injected early enough after operation (mature hypophysectomized 

 male rats); and (4) the pituitary of the normal male rat secretes only follicle-stimu- 

 lating hormone (at least the secretion of luteinizing hormone has not been detected 

 in the living animal, although small amounts of luteinizing hormone may be recog- 

 nized by implanting the male pituitary). 



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