G R O W T H I N D U C E D B Y D A M A G E
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FIG. 7. Wounds made in female C57BL/6J mice with growing hair follicles. The
second hair growth stimulation surrounding healed wounds made in mice 10 days
after plucking. The skin has been clipped to emphasize the hair growth around the
wound. The hair follicles in the clipped area are in the resting phase (from Argyris,
1964).
around the wound appear to be unaffected and continue to grow and
produce hair. A b o u t the eleventh to twelfth day after wounding, the
growing hair follicles finish their growth phase and enter the resting
phase of the hair growth cycle. Thus wounding, as predicted, so far has
had no effect on the growth hair follicles. However, within 9 days (Fig.
7) after the growing hair follicles enter the resting phase, the ones surrounding the healed wound are stimulated to grow again (Argyris, 1962,
1964). Thus one might conjecture that the plucked growing hair follicles
surrounding the wound, do, in fact, receive a growth-promoting stimulus
from the wound. But since they are already growing, this second stimulus
for growth is somehow stored until the growth initiated b y plucking is
completed. When the growing hair follicles complete their growth phase
and enter the resting phase, the second set of instructions "to g r o w " is