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23
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depth is near the base of the hair follicle which comprises
“he deepest reservoir of epithelial cells of the germinal
layer, it was suggestive that this might be a critical
rogion in the observed carcinogenesis.
The suggestion gained
significance from the observations that most of the tumors
.re@ Similar to hair
follicles,
and that in the non-ulcerogenic
dose range the number of tumors per rat was
vatio
(1,//2000-1/4000)
follicles.
in nearly constant
with the number of atrophied hair
Thus the carcinogenesis in this experiment
was remarkably correlated with the dose to and specific
damage of a particular skin structure.
When exposures were
made with stripe and sieve satterns of roughly 1 mm scale,
geometrical effects were observed:
most notably the cancer
rad but net
at
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oa
a
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induction in the sieve geometry was suppressed at doses of
cf£ 2300
rad.
Tne reduction, however,
was again consistent with the reduction in damage as characterized
by atrophied hair follicles.
,
To summarize this important experiment, a high incidence
of cancer was observed after intense local doses of radiation,
and the carcinogenesis was proportional to the damage or
disordering of a critical architectural unit of the tissue,
the hair
follicles,
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