12
THOMAS S. ARGYRIS
somehow released and the hair follicles are stimulated to grow a second
time.
The objection may be raised that the second hair growth stimulation
occurs because the wound has not actually completely healed when the
growing hair follicles enter the resting phase. The partially healed wound
is still capable of producing growth-promoting substances that again
stimulate the growth of the surrounding hair follicles. To rule out this
possibility, hair growth has been initiated by plucking, and wounds have
been made in the center of the plucked area 3-4 hours later. The plucked
hair follicles require at least 21 days to complete their growth phase
(Chase, 1954). This is ample time for the wounds to heal (Argyris,
1956a). Observation of the mice 24 days after plucking and wounding
reveals that the plucked hair follicles have completed their growth and
have entered the resting phase. Histological examination of the wounds
reveals that the wounds have healed and only small scars are left. Within
a few days the hair follicles immediately surrounding the healed wound
are stimulated to grow again. Thus an open wound is not required for
hair growth stimulation to occur a second time. Therefore, it can be
suggested that growing hair follicles surrounding a wound appear to be
able to "store" a growth-promoting cue from a wound which can stimulate the growing hair follicles to grow a second time after they enter the
resting phase. Of course, it has not been excluded that the second stimulation is simply caused by the release of growth-promoting substances from
the scar tissue itself or that the presence of the scar in some way initiates
hair growth. For example, if the loss of an inhibitor can initiate hair
growth (Bullough, 1962; Chase, 1954, 1958), then hair growth could
begin around a scar since the concentration of an inhibitor would be
lowest there because of the absence of hair follicles within the scar. This
problem merits further investigation.
3. The Response of the Connective
Tissue
The response of the connective tissue of the skin to injury has been
one of the most extensively investigated problems in wound healing and
many excellent reviews may be found on this subject (Arey, 1936;
Allgower, 1956; Grillo, 1964; Glucksmann, 1964; Russell and Billingham,
1962). Therefore, we shall limit ourselves to presenting only a brief
outline sufficient to make our subsequent discussion of the mechanism of
the initiation of connective tissue growth understandable.
Recent evidence has demonstrated that the dermal cells do not respond
to damage by proliferation (Argyris, 1956a; Glucksmann, 1964). In
THOMAS S. ARGYRIS
somehow released and the hair follicles are stimulated to grow a second
time.
The objection may be raised that the second hair growth stimulation
occurs because the wound has not actually completely healed when the
growing hair follicles enter the resting phase. The partially healed wound
is still capable of producing growth-promoting substances that again
stimulate the growth of the surrounding hair follicles. To rule out this
possibility, hair growth has been initiated by plucking, and wounds have
been made in the center of the plucked area 3-4 hours later. The plucked
hair follicles require at least 21 days to complete their growth phase
(Chase, 1954). This is ample time for the wounds to heal (Argyris,
1956a). Observation of the mice 24 days after plucking and wounding
reveals that the plucked hair follicles have completed their growth and
have entered the resting phase. Histological examination of the wounds
reveals that the wounds have healed and only small scars are left. Within
a few days the hair follicles immediately surrounding the healed wound
are stimulated to grow again. Thus an open wound is not required for
hair growth stimulation to occur a second time. Therefore, it can be
suggested that growing hair follicles surrounding a wound appear to be
able to "store" a growth-promoting cue from a wound which can stimulate the growing hair follicles to grow a second time after they enter the
resting phase. Of course, it has not been excluded that the second stimulation is simply caused by the release of growth-promoting substances from
the scar tissue itself or that the presence of the scar in some way initiates
hair growth. For example, if the loss of an inhibitor can initiate hair
growth (Bullough, 1962; Chase, 1954, 1958), then hair growth could
begin around a scar since the concentration of an inhibitor would be
lowest there because of the absence of hair follicles within the scar. This
problem merits further investigation.
3. The Response of the Connective
Tissue
The response of the connective tissue of the skin to injury has been
one of the most extensively investigated problems in wound healing and
many excellent reviews may be found on this subject (Arey, 1936;
Allgower, 1956; Grillo, 1964; Glucksmann, 1964; Russell and Billingham,
1962). Therefore, we shall limit ourselves to presenting only a brief
outline sufficient to make our subsequent discussion of the mechanism of
the initiation of connective tissue growth understandable.
Recent evidence has demonstrated that the dermal cells do not respond
to damage by proliferation (Argyris, 1956a; Glucksmann, 1964). In