me ne owned CAPELUMIICS, 2 Small trace dose of 4+91I in addition to the
Areated thymidine bas been given to the animals four hoursbefore sa
ioe.
Autoradiographs prce-ured from microscopic sections promptly after the
rimove
of the thyroid ser:« <o identify any local areas in the gland where 131
utilization is dit’..ont from the rest of the gland.
Because of the shért
half
life of 131I, this -s0tope disappears from the microscopic sections after two
or three months.
iow autoradiographs then prepared from other microsce
acent to those used to demonstrate 1911,will show only the location df
tiated thymidine. Subsequent comparison of the two autoradiographs
microscopic sections,which are almost identical, reveals two types of
about the same cluster of cells which appear in both preparations.
the
from
amatic
We have several large groups of rats whose thyroids have been
Others are stimulated acutely for a few days berore
ice. Still
remain unstimulated, except for the intrinsic stimulus which the animal fy
receive as a result of diminution in hormone
by the radiated thyrpid.
oe
sporvtanmouslYe ALthough
ohthe
theincidence’ of necplasms
saees Snood byLAT act
SeecigdfieantTY om» han lesions have bean found their present
more
ieant.
Rats weighing 100-130 grams were fi-st used with ultimate poor
survival,
owing to an epidemic of pulmonary infection; howsver, the expected bizarge nuclear
forms and some giant nuclei, which had previously beer shown to contain noes ive
amounts of chromatin, did appear.
labeled thymidine.
Many of the large nuclear forms took gp the
More recently, weanlings were prepared by giving doses of 1311 from|2.5
microcurie to 40 microcurie doses. Each ret has been identified and its
individual uptake of the dose determined so that the individual amourt o:
radiation can be more precisely known. Tus far, autoradiogrephs of rat jt oad
rediated ten months or less before sacrifice have been reviewed.
As we lve
previously observed, hypertrophy of the gland may be produced by goitre
for
quite some time after the 1321 is given, but after a considerable lag
Cong
gurge of mitotic activity after several sonths cf recovery, as we had p
osuly
described in an earlier series, is confirmed. ‘<t is apparerrtly at this time that
hypertrophy of the gland can be produced even though it carmot be produce! later.