-
13
-
Such follicles often contained darker staining colloid.
such follicles have essentially no uptake of
131
I.
Autoradiogrfphs showed that
The cells compribing the wall of
such a follicle are thus functionally different from others nearby
Such giant follicles may be found containing a cluster of cells aris
in the wall rather than the normal single layer of cells lining the
t are functioning
from one local
est of the follicl
Some of the masses of cells may be forming papillary tufts prot
into the follicle
These cells have a discernably higher incidence of nuclei bearing
*H-TdR label thar
cells in other parts of the wall of that follicle or in other folli
es nearby.
follicle appears to enlarge to accomodate the expanding papillary 1
ion within. Ul-
The
timately the cells ofthe parent follicle are replaced by commective tissue forming a
capsule as the total mass cames to occupy more of a lobe.
Although there may be- quite
a mmber of the enlarged non-functioning follicles in a single irra jiated
thyroid and «
a few of the lesions described above appear in a single thyroid, buq they are in diffe:
ent stages of development in a given animal.
This is the evolution of papillary neo-
Plasms.
The follicular neoplasms appearto evolve much as the papill
follicles develop among the papillary structures.
lesions.
Tiny
The parent folli le contimes to
|
expand until the structure appears to be an encapsulated follicular adenoma.
Multiple
lesions are again seen in a single thyroid, where as solid cellular lesions are most
often single but may be accampanied by papillary or mixed papillary and follicular
lesions in the same thyroid. The application of autoradiography us ing 131) and 4y-TaR
separately prepared from adjacent sections of tissue, with such obs prvations on very
large mmbers of rats, have made the described sequences of develophent rather obvious
The material acquired for these observations was based on four expe riments composed
of several Immdred animals each and lasting 16 to 22 months.