Discussion 147 



there is a considerable number of collagen fibres. So I do not think you 

 can avoid it that way. 



Villee: No, all we can do is minimize it. 



Dempsey: Another comment I wanted to make was with reference to 

 the problem of ageing. If I understand correctly the placenta does not 

 show very great signs of ageing because it can still do a great many 

 things, albeit perhaps not quite as rapidly as it did earlier in pregnancy. 

 This somehow does not prove to me that the placenta is not in fact 

 aged, because I think one might also say that an 80-year-old man can 

 still do a great many things. 



Villee: You may remember, Prof. Dempsey, that I said that if we may 

 equate ageing with these changes, or equate these changes in chemical 

 function with ageing, then the placenta undergoes ageing. 



Dempsey: Yes. I simply was interested in the manner of ageing. 

 I am sure that there are a great many functions which persist at a 

 perfectly normal rate in an aged organism. That is, there are some 

 functions which are not limiting in an ageing individual. For example, 

 I believe that conduction velocity does not decrease with ageing in the 

 nerve ; it either conducts or it does not conduct. But yet there are age 

 changes in the nervous system in the sense that nerve cells fall out. So 

 a particular biochemical or physiological event may or may not show 

 changes with chronological increase in age. 



Villee: Quite right. I chose these particular functions since these 

 have to do mostly with the release of energy, and I felt that if we did 

 demonstrate marked changes in these, then I would believe that perhaps 

 the tissue is really ageing in any sense you want to say. Perhaps we 

 should have started the colloquium by defining ageing. 



Wislocki: In my own presentation, earlier this morning, I discussed 

 the definition of ageing with respect to the peculiar mode of growth and 

 structure of the mammalian placenta. We do, indeed, have to define 

 what we mean by ageing in the case of the placenta. 



