108 General Discussion 



collagen fibres remaining. So, under the electron microscope the struc- 

 ture is very difterent from ordinary collagen with its perfect fibres — in 

 bundles and cross striations. 



Albertini: May I show an electron microscopic pattern of a skin biopsy 

 with senile keratosis and very typical so-called elastosis which we also 

 call "elastoid degeneration". 



When I examined the slide in the light microscope I saw the same 

 tremendous masses of "elastoid material" as Dr. Lansing has already 

 shown. Using the low power of the electron microscope (Fig. 1) we 

 again see the same masses. But with higher power (Fig. 2) it becomes 

 obvious that this material must be degenerated collagen and not 

 degenerated elastic fibres. Don't you think so? 



Lansing: But in between the bundles of collagen, do you think the 

 tissue is actually empty there or do you think perhaps you have a rather 

 fragmented section? 



Tunbridge: Of course, when one employs the electron microscope, 

 obviously some of the spaces are artifacts due to the technique. Some 

 may be intracellular substances and matrix of which we know very little 

 and cannot get rid of. But I think that you can compare section with 

 section. I do not know if Prof. Albertini will agree with me on that. 



Albertini: Yes, I do. 



Lansing: The very low level of electron density in the area represented 

 by what I call space is awfully suggestive of naked collodion membrane 

 and not ground substance which has a significant electron density. I 

 think that we are not dealing here with a continuous section and I think 

 the only way one can answer that would be to have two sections side by 

 side — a thick section in the phase microscope and an adjacent serial 

 section cut much thinner and introduced into the electron microscope 

 to enable one to check area against area. That's what we've been 

 doing and we don't get empty spaces. 



Cowdry: Dr. Lansing, could you say a word about purifying the 

 enzyme? 



Lansing: Using organic solvents under standardized conditions of 

 precipitation, we have a material that seems to be free of trypsin, and 

 is well along towards purification, but it still has a long way to go. I 

 think in another few months we may be able to talk more fuU}^ about it. 



Verzdr: I am glad that the discussion has now reached basic problems 

 of the ageing of cells and even of proteins. I think that the admirable 

 work of Dr. Lansing is really of a more general importance than when he 

 speaks only of elastin and collagen. The loss of elasticity is so general in 

 ageing tissue that one can find it in skin, in muscle, in blood vessels, and 

 even in nerve. I think that this leads to the basically important question 

 of the changes of tissue adaptation which might be caused by changes 

 in the proteins. 



I would also like to say that a lot of time was spent in our laboratory 

 with elastase estimations in young and old animals, and large differences 

 in the pancreases of young and old animals were found but unfortunately 

 they were not related to age. 



