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The Specificity of the hair papilla in the rat.

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The Specificity of the Hair Papilla in the R a t
Departments of Anatomy, College of Dentistry and the Graduate School
of Arts and Science, New York University
A flap of skin on the dorsum of Long-Evans rats under anesthesia was
turned back, the panniculus was excised and hair bulbs in the growing stage with the
enclosed papillae were removed with scissors from a 0.5 cm square area. The flap was
returned to its original position and the cut edges were sutured. Depapillated areas
were biopsied at intervals following the operation, fixed in acetone and histologically
prepared to study the distribution of alkaline phosphatase, glycogen changes, growth
and differentiation.
The hair recedes soon after the operation and is surrounded by the outer sheath
cells, some of which remain below the receding hair as an epithelial strand. The
latter begins growth and elongation 5-6 days after the operation. Differentiation
follows and a fragile hair is formed, but the bulbs seldom have a papilla.
The connective tissue in the subcutaneous area apparently cannot be stimulated
or does not have the potentiality to become a papilla. Since only a fragile hair is
produced by the depapillated follicle, the papilla is very important for the growth of
the hair. These observations indicate that the papilla is endowed with special potentialities or has a specificity.
When the papilla of the hair follicle in
the rat is studied, one is impressed by how
it differs in quality and reaction from the
surrounding tissues. In the first place, it
contains more alkaline phosphatase. Secondly, it is more difficult to stain with
Van Gieson. It persists from hair generation to the next generation as do the cells
of the outer root sheath which are the
progenitors of the new epithelial hair bud
(Butcher, '64).
There is no evidence that the surrounding connective tissue possesses the potentiality of becoming a papilla, if the latter
is removed. What effect the lack of the
papilla has on the formation and growth
of hair by the epithelial portion of the
follicle has likewise never been ascertained.
The purpose of this investigation is
therefore to learn ( 1 ) if the papilla possesses specac properties; (2) if other connective tissue will become a papilla after
removal of the papilla; ( 3 ) the importance
of the papilla.
To obtain information on these questions regarding the papilla the following
procedures were used. When the second
hair buds had started growth at about the
age of 35 days in Long-Evans rats, an
anterior-posterior incision was made in the
ANAT. REC., 151: 231-238.
skin of the dorsum in animals under Nembutal anesthesia (fig. 1 ), and a flap of skin
was turned back. By placing the finger
under the flap, the panniculus carnosus
can easily be seen in the dissecting microscope. The panniculus was excised with
fine forceps and scissors, exposing the
roots of the hair (fig. 2 ) . The bulbs with
the enclosed papillae were then removed
with iridectomy scissors from a 0.5 cm
square area. Since the blood supply survives mainly in the dermis, the denuded
area must be small or it will necrose. The
skin was returned to its original position
and the cut edges were sutured. The thinner denuded area could easily be identified
by palpation. The bulbs, papillae and panniculus were removed in nearly 50 rats.
Depapillated areas were recovered from
different rats at various intervals following the operation and the biopsies were
fixed in AAF or acetone. For alkaline phosphatase study, the method of Gomori was
used. The distribution of glycogen was
demonstrated with the PAS method using
malt diastase for the control. Hematoxylin
and eosin were used as a general histological stain.
After the operation the follicles are seen
to be completely denuded of the bulbs and
papillae (fig. 3). Of course the bulbs of
some of the smaller follicles whose extent
is not so deep will escape incision and will
be the source of some of the fine hairs
seen later on the area.
Three days after the operation the cells
of the outer sheath have surrounded the
receding hair. The smaller hairs because
of their extent are less often damaged
(fig. 4). Figures 3 and 4 show the typical
injury and recovery. In taking the biopsy,
a cleavage of the tissues occurs at the
wound site basally.
Some glycogen staining material is
found in epithelial cells around the old
hair. This material will gradually disappear and is probably used up in the
keratinization of the club of the hair
(fig. 6 ) .
A good typical condition four days after
the operation is shown in figure 5. Note
how the cells of the outer sheath have
coalesced together below the receding hair.
The blood vessels of the subcutaneous tissue have been largely eliminated by the
injury and the vascularity is supplied by
vessels situated in the dermis.
By four days after the operation most of
the glycogen has been used (fig. 7) and
only traces remain in the former cells of
the outer sheath which are deep to the
resting hair.
Apparently the epithelial strand deep to
the hair never recedes to the extent or to
the position of the bud found in a normal
resting follicle (fig. 8). It begins growth
when it has partially moved to a resting
level (fig. 9). Note there is no papilla in
relation to the epithelial growth. Occasionally, the bud will deviate in different
directions in its growth, giving the impression that it is seeking a papilla.
The epithelial portion continues to elongate; then keratinization begins and a
fragile hair is formed (fig. 10). The bulbs
often turn or take a tortuous course (fig,
11 ) but most of them never have a papilla.
In figure 12 is seen a follicle with no
papilla. The connective tissue sheath is
well demarcated because of its alkaline
phosphatase content. Epithelial cells at
the base of the follicle contain numerous
degenerate globules and poor keratinization is resulting. Another such follicle is
shown in figure 15. It is blackened due to
its alkaline phosphatase reaction. Blood
channels are apparent to the right and
left of the follicle.
A small follicle with no papilla is seen
in figure 13. In this instance the subcutaneous tissue has become very dense.
Such follicles with no papilla are often
associated with an environment of very
dense subcutaneous tissue.
The follicles finally recede to a resting
level and fine hair will often be found in
them. As seen in figure 14 the area remains covered with few fragile hairs.
Upon removal of the papilla, the surrounding connective tissue does not become another papilla. This observation
revives the old problem which has been
the subject of many investigations - does
the tissue of the papilla possess a specific
controlling influence (Cairns and Saunders, '54), or does the ectoderm and mesoderm act conjointly in initiating a feather
papilla (Saunders and Weiss, '50).
Hardy ('49) observed, by tissue culture,
that all stages of hair development were
produced from undifferentiated ectoderm
with some underlying mesoderm. Cohen
('61) found that hair follicles were produced by the ectoderm under the influence
of whisker papilla.
The present results seem in conflict
with those of Breedis ( ' 6 3 ) and my own
('59) studies. An account of Breedis' approach and observations in the rabbit were
found when this investigation was nearly
completed. His operations varied from the
present excisions in that he apparently
removed much more of the hair follicle.
He found many new follicles, which apparently contained papilla, forming from
the surface epidermis. Similar observations were made by me in the rat ('59).
The question arises how new papilla can
be formed in one instance and not in the
present experiments. The connective tissue in the subcutaneous area apparently
cannot be stimulated or does not have the
potentiality to become a papilla while in
the dermis residual papillae analagen may
persist or newly formed buds from the
surface epidermis may have some inductive power.
Failure of the formation of a papilla in
the present experiments does not seem to
be due to any deficiency cn the part of the
epithelial portion of the follicle for the
epithelial bud grows and forms a fragile
keratinized hair.
These investigations indicate how very
important the papilla is for the growth of
the hair.
Crounse and Stengle ('59) also concluded after depapillating human hairs
that the dermal papilla is necessary for the
maintenance of the organization of the
hair root. Without the presence of the
papilla growth materials are unavailable
and a fragile hair results in the present
experiments. It is quite possible that the
temporary stimulation of irritants on hair
growth is via increased blood supply which
provides more growth materials than an
abortive papilla is able to supply.
Breedis, C. 1963 Differentiation and redifferentiation in skin. Conf. on Biol. of Cutaneous
Cancer. National Cancer Institute, Monograph,
10: 21-33.
Butcher, E. 0. 1959 Hair growth and hair
regeneration. Annals of the New York Academy Science, 83: 369-377.
1964 The effects of thallium and hair
growth in the rat. J. SOC. Cos. Chem., 15:
Cairns, J. M., and J. W. Saunders, Jr. 1954
The influence of embryonic mesoderm on the
regional specification of epidermal derivatives
i n the chick. J. Exp. Zool., 127: 221-248.
Cohen, J. 1961 The transplantation of individual rat and guineapig whisker papilla. J.
Emb. and Exp. Morph., 9: 117-127.
Crounse, R. G., and J. M. Stengle 1959 Influence of dermal papilla on survival of human
scalp hair roots in an heterologous host. J.
Invest. Derm., 32: 477-479.
Hardy, H. M. 1949 The development of the
mouse hair in vitro with some observations on
pigmentation. J. Anat., 83: 364-383.
Saunders, J. W., and P. Weiss 1950 Effects of
removal of ectoderm on the origin and distribution of feather germs in the wing of the
chick embryo. Anat. Rec., 108: 581.
Photograph shows the reflection of a flap of skin.
Area of panniculus carnosus has been removed, exposing the roots of
the hair.
Section showing the extent to which the bulbs and papillae were
removed. X 70.
Condition of follicles is shown three days after the operation. X 70.
Shows hair four days after operation with cells from the outer root
sheath below the follicle. x 70.
PAS staining material persists in outer sheath cells around the old
hair. x 120.
Four days after the operation most of the glycogen has disappeared.
x 120.
Earl 0. Butcher
Epithelial cells begin increasing usually on the fifth day after
the operation. X 70.
Epithelial cells do not move to the level found i n the normal
resting follicle. Note the absence of the papilla. X 70.
Follicles without papillae are forming fragile hairs 15-20 days
after the operation. X 70.
12 and 15
No papillae are seen i n sections treated for their alkaline
phosphatase reaction. X 70.
Follicles without papilla are often surrounded by dense subcutaneous tissue. X 70.
The area from which the papillae were excised produces a
few fine hairs.
Earl 0. Butcher
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papilla, rat, specificity, hair
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