KADIATION PROTECTION IN SKIN OF MICE 311 



whitening at all so that the protection is not only on hair growth but also on hair 

 pigmentation. 



BERENBLUM: You wiU recall that in one of the experiments that I have already described 

 we gave C57BL mice a single dose of 400 r; the next day we took tissue cells from them 

 and injected large amounts of homogenates into normal C57BL, some of which were then 

 given urethane and so on. We found that the recipients of these injected tissues developed 

 greying of the hair very early. 



chase: Yes, I am quite aware that this greying phenomenon can be caused by many 

 things about wliich we know very little. There has been some indication that occasionally 

 one can give a certain type of poison and get some greying, but it doesn't happen con- 

 sistently. In regard to Prof. Bacq's story, remember that the greying effect is greater if 

 you irradiate the resting foUicles; these follicles are more sensitive and there wiU be a 

 much greater effect. On growing follicles the effect is less. However, since you didn't get 

 any greying in that area with 550 r, were these hairs actually replaced at all? Was it 

 possible that these were the hairs that were there already and simply staying as resting 

 hairs? These mice were 5-8 days old. At 5 days they had no hair, but at 8 days they 

 had a nice cover of hair. But at 5 days the hair is growmg. Some hairs remained dark and 

 the rest disappeared. If hairs are growing and a dose of 550 r is then given, I would expect 

 you to get about 15% white hair. 



CURTIS: I would like to ask Prof. Bacq about his synovial fluid. Does he actually tliink that 

 a compound in synovial fluid penetrates to all the cells in the skin? 

 BACQ: We believe that some type of extra- cellular protection is operatmg. Apparently, but 

 I think Dr. Brinkman knows more about this, the growth of the foUicle is dependent, 

 partly at least, on these extra- cellular macromolecules which siuround the hair bulb. I 

 do not think they do penetrate the cell, it is probably a different mechanism of protection 

 unless you thinli that this is not simply protection since it can occur even after irradiation. 

 BRINKMAN: I think it is a general experience that when the hair growth cycle starts the 

 first thing that you can see is an accumulation of mucopolysaccharides of a very special 

 kind in the hair bulb and if tliis is depolymerized by irradiation, then the growth of the 

 hair is changed. If you the ninject mucopolysaccharides, the hair starts to grow in the 

 injected places, as has already been shown by Karl Meyer. The best mucopolysaccharide 

 is heparin monosulphate. It may be the function of the mucopolysaccharide layer to 

 convert globular into fibrous molecules. 



MOLE: Prof. Brinkman earher suggested to Prof. Lamerton that the reason why he got 

 acquired radioresistance in the intestine was a local Ubertation of serotonin. May I ask 

 Prof. Bacq if serotonin works m this system? 

 BACQ: Yes, it does. 



