70 Discussion 



Bald: I was very interested in hearing Prof. Verzar's report of his 

 finding that in the sciatic nerve heat contraction takes place between 

 76° and 92°, whereas heat contraction of collagen takes place at a lower 

 temperature ; we have found it at 62-70°. This finding suggests that some 

 protein material which belongs to the nerves contracts, and that can 

 only be the axis cylinder. It would be interesting to carry out some 

 work to clarify this problem, because the contraction of collagen has 

 given some insight into the structure of collagen. We have found that 

 contraction of collagen fibres takes place, and that relaxation follows 

 after contraction. Now, at the time of contraction, mucopolysaccharides 

 are dissolved and at the time of relaxation the pro-collagen is dissolved, 

 and we found that, in old age, relaxation does not take place because 

 the pro-collagen (which makes up 20 per cent of the collagen fibres) 

 cannot be dissolved. Since this has given an insight into the structure of 

 collagen, I think that if we could prove that a similar alteration takes 

 place in the nerve fibres then we would have a clear idea of the structure 

 of the axis cylinders. 



Nicolaysen: Prof. Verzar, can you take fibres out of the living body 

 (of a young rat, for instance) and preserve them deep-frozen for a couple 

 of years, say, and then test them? 



Verzar: I have kept them a month in the ice-chest and they remained 

 the same. 



Gillman: In relation to Prof. Verzar's contribution it may be worth- 

 while thinking of the possibility of testing, by his techniques, alterations 

 in collagen in scars as they age. Admittedly, Abercrombie and co-workers 

 (Abercrombie, M., Flint, M. H., and James, D. W. (1956). J. Embryol. 

 exp. Morphol., 4, 166) have recently indicated that a wound can undergo 

 contraction in the absence of collagen deposition in scorbutic animals ; 

 but at the same time there would seem to be considerable indication 

 that in the latter stages of the healing of certain types of wounds, in 

 humans and rabbits at any rate, there is considerable contracture which 

 seems to be associated with diminishing cellularity in the healing area. 

 In scar tissue in different organs in the body there are morphological and 

 tinctorial changes with the ageing of the scar tissue; apart from the 

 alteration in cellularity (which everyone accepts as one of the phenomena 

 of ageing scars) there are also alterations in the tinctorial reactions 

 indicating the development of fibres which "take" elastic stains. I am 

 not by any means implying that everything that stains with elastic stains 

 is elastic tissue. In fact we have called such altered collagen "pseudo- 

 elastic" tissue (Gillman, T., Penn, J., Bronks, D., and Roux, M. (1955). 

 A.M.A. Arch. Path., 59, 733). And whether you find such pseudo-elastic 

 tissue in a scar or following chronic injuries (like those in the skin due to 

 ultraviolet or X-ray irradiation), or in an organ like the liver, where 

 long-standing cirrhosis is also associated with an alteration in the colla- 

 gen which acquires "elastic" staining, or whether in arteries, we have 

 shown that the same thing seems to occur in all instances when collagen 

 ages. One would be interested to know (and I think that Prof. Verzar's 

 methods would give some indication) whether it might be worthwhile, 

 both experimentally and in man, to test the reactivity of collagen in scars 



