GROWTH INDUCED BY DAMAGE
21
results in the removal of the tissue surrounding the advancing edge of
the growing tumor and thus results in the local loss of organ mass as
occurs after damage (Argyris and Trimble, 1964a,b; Kollar, 1963).
2. The Inability of the Loss of Mass to Initiate Growth of Tissues
We have studied the effect of the local loss of mass produced by an
invading tumor on the stimulation of hair growth in the skin, a process
that we know occurs in wound healing.
Mice of the C57BL/6J strain with resting hair follicles have been
subcutaneously inoculated with Ehrlich ascites tumor (Argyris and
Trimble, 1964a). To insure that the tumor would not invade the underlying musculature and spinal column, the undersurface of the skin has
been scraped with the syringe needle just before inoculation of the
tumor. This damage facilitates the preferential invasion of the overlying
skin by the tumor. Within a few days the ascites tumor has been transformed into a solid nodule and has invaded the overlying skin. The
invasion of the overlying skin is usually completed within 2-3 weeks
after tumor inoculation. Figure 9 shows that at this time the tumor has
completely replaced the skin and ulceration has occurred. Since the skin
has been effectively removed, one would expect that the resting hair
follicles surrounding this area would be stimulated to grow if the loss of
skin is an effective stimulus for hair growth. In no case has the stimulation of hair growth been observed. Thus the loss of skin mass is not a
sufficient cue for the stimulation of hair growth. But, before we can
accept this conclusion a number of objections must be met.
First, the objection may be raised that the reason hair growth stimulation does not occur, is simply that the tumor has debilitated the mice, so
that they are too weak to mount a proliferative response, and not that
the loss of skin mass is not a legitimate cue for initiating hair growth.
It is also possible that the tumor inhibits the resting hair follicles from
growing because it secretes toxic substances, growth inhibitors, or it
competes more effectively than the resting hair follicles for available
energy and/or metabolites necessary for growth. Daily checking of the
mice has shown that the subcutaneously inoculated Ehrlich ascites
tumor has no obvious deleterious effects on the mice. In addition, a group
of mice has been inoculated subcutaneously with the Ehrlich ascites
tumor and another group with ascites fluid alone. The body weights of
the mice in each group have been measured daily for 40 days. At the
end of this period, the mice have been killed, half of them have been
used to determine wet and dry weights of the kidneys, heart, lungs, liver,
21
results in the removal of the tissue surrounding the advancing edge of
the growing tumor and thus results in the local loss of organ mass as
occurs after damage (Argyris and Trimble, 1964a,b; Kollar, 1963).
2. The Inability of the Loss of Mass to Initiate Growth of Tissues
We have studied the effect of the local loss of mass produced by an
invading tumor on the stimulation of hair growth in the skin, a process
that we know occurs in wound healing.
Mice of the C57BL/6J strain with resting hair follicles have been
subcutaneously inoculated with Ehrlich ascites tumor (Argyris and
Trimble, 1964a). To insure that the tumor would not invade the underlying musculature and spinal column, the undersurface of the skin has
been scraped with the syringe needle just before inoculation of the
tumor. This damage facilitates the preferential invasion of the overlying
skin by the tumor. Within a few days the ascites tumor has been transformed into a solid nodule and has invaded the overlying skin. The
invasion of the overlying skin is usually completed within 2-3 weeks
after tumor inoculation. Figure 9 shows that at this time the tumor has
completely replaced the skin and ulceration has occurred. Since the skin
has been effectively removed, one would expect that the resting hair
follicles surrounding this area would be stimulated to grow if the loss of
skin is an effective stimulus for hair growth. In no case has the stimulation of hair growth been observed. Thus the loss of skin mass is not a
sufficient cue for the stimulation of hair growth. But, before we can
accept this conclusion a number of objections must be met.
First, the objection may be raised that the reason hair growth stimulation does not occur, is simply that the tumor has debilitated the mice, so
that they are too weak to mount a proliferative response, and not that
the loss of skin mass is not a legitimate cue for initiating hair growth.
It is also possible that the tumor inhibits the resting hair follicles from
growing because it secretes toxic substances, growth inhibitors, or it
competes more effectively than the resting hair follicles for available
energy and/or metabolites necessary for growth. Daily checking of the
mice has shown that the subcutaneously inoculated Ehrlich ascites
tumor has no obvious deleterious effects on the mice. In addition, a group
of mice has been inoculated subcutaneously with the Ehrlich ascites
tumor and another group with ascites fluid alone. The body weights of
the mice in each group have been measured daily for 40 days. At the
end of this period, the mice have been killed, half of them have been
used to determine wet and dry weights of the kidneys, heart, lungs, liver,