The Mechanisms of Senescence 



into senescence. No doubt if explants could be cultivated in 

 media exactly simulating the chemical and physical environ- 

 ment and its changes through all the stages of development, they 

 would pass through all the normal phases of in vivo histology. 

 The point of interest to the gerontologist is to know how far it 

 is possible to maintain a status quo at any point. Analysis of the 

 power of tissues to mark time developmentally while retaining 

 function requires more elaborate methods of organ and tissue 

 culture than are so far available, but the lead given by Carrel 

 in applying these techniques to age-processes has hardly been 

 pursued with the vigour it merits. Gey (1952) has recently 

 referred to the in vitro culture of 'thyroid, parathyroid, adrenal 

 cells, and the germinal epithelium of the ovary 5 even to the 

 production of follicles, but these findings remain contentious. 



6-2 Endocrine Senescence 



6-2-1 GENERAL 



The early discoverers of hormones were fully convinced that 

 they had in their hands the key to the prevention of senescence 

 in man. The fact that little of their enthusiasm persists today is 

 due very largely to the manner in which the confluence of two 

 deeply emotive subjects — ageing and the gonad — affected scien- 

 tific judgement in the early years of the century. The hypotheses 

 of the rejuvenators were in many respects reasonable, if their 

 published claims were not. In any discussion of endocrine sen- 

 escence it is probably worth restating ( 1 ) that organ and tissue 

 grafting are appropriate and fully respectable techniques for 

 the investigation of senile change, and that they have given 

 misleading answers chiefly because the wrong questions were 

 asked, (2) that the use of hormones in the palliation of senile 

 changes in man, although it is largely ineffective, was a reason- 

 able experiment which has not yet been exhausted, and (3) 

 although gonadal 'senescence' does not 'cause 5 somatic sen- 

 escence (this was self-evident in antiquity, from the life histories 

 of eunuchs, long before testosterone was found to be unavailing in 

 reversing general senile decay), it is a highly important model 

 process, and a relatively accessible one for further study. 



171 



