Evening star., 1955-01-17
E1ch Organ Produces
Growth Inhibitors
Substances controI,
Nuke heuIthy Body
By Thomos Z. Henry

Each organ Of the body produces ~
own growth inhihitors TO prevent 4
from over-srowing.
Finding Of these hitherto unknown
inhibitors, which are released into the
blood stream when cells divide. was
announced to the American Association
for the Advancement Of Science re-
Gently by DR.. Paul Weiss Of the Rookie
feller Institute. and now chairman Of
the biology section Of the National Re-
search Council
Once 8 certain concentration Is
reached, further growth is prevented
for the time being Each organ. include
ing each type Of blood cell, produces
inhihitcrs specific to itself alone.
These substances appear TO be pri-
mary factors IN controlled rather than
chaotic growth. 50 that the healthy
body Is perfectly balanced.
''Tlis principle. said Or. weiss.
anow explains why after removal Of
part of an organ the remaining portion
tends TO show an immediate spurt Of
compensatory growth. It also explains
the otherwise paradoxical fact that the
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organ into the body promotes growth
Of the corresponding organ in the
injected body.
Liver as an Example.
For example. the biologist explained.
II half the liver is removed only half
the liver inhibitors are being produced.
In the case Of the injections the
crushed cells lower the concentration
Of the inhibitors.
But, Or. Weiss said, this Is far from
giving the whole complex story OF
growth IN which many processes still
unknown probably are involved. For
instance. he said. +in such q seemingly
elementary growth process as the for
nation Of q local skin fold at least fyo
separate components can be observed
cell aggregation, cell enlargement, cell
multiplication. tissue realieninent and
accumulation OF functional products.
The common habit Of eduating growth
with protein synthesis Is confusing.
The process Of producing more proto-
plasm. which Is growth In the strict
sense, Is something quite different from
production OF functionally specialized
products BY protoplaslli. although both
involve protein synthesis.
1.-THE primary event In all proto-
plasmic reproduction, seems to be the
multiplication Of genes. followed by ea-
largemeflt Of the cell nucleus. This
nucleus Is not only the controlling CEN
ter but the actual source Of the growth
Of the cell. ! have experiraentaliy dem-
oyistrated this for nerve cells whose
long, fihrous extensions can be starved
by throttling their connections with
the cell nucleus In other cells, In which
growth is accompanied BY cell division.
growth Is again the primary event.
This has been shown by stimulating
skin growth In q localized spot by q
growth h-promoting factor exuded from
nerves. A wave OF cell endorsement is
seen TO precede wave Of cell multipli-
cation.
Further Experiments.
"Further experiments indicated that
the apparent growth stimulation OBJ
tanned with various agents amounts in
( reality to partial or total removal Of
something which normally keeps tis-
sues from growing at their maximum
capacity. It is doubtful II growth can
actually be boosted In the sense Of
stepping up the productive potential
Of the cell. Attention thus turns In
creasingly from factors that make q
cell grow to factors that keep 1t from
growing or reiuce the growth rate Of
q tissue.
Growth regulation IS achieved by
no single mechanism but by q number
Of controls. One. still ill-explored. Ii
supply of the specific nutrients. for
each cell type seems to, have Its own
specific requirements Another control
Is exerted BY tormones. TO which each
cell and organ type responds according
to its own particular characteristics.
However. Or. Weiss declared, the
production of the specific cell inhibitors
by the cells themselves may be the
most important process Of all.