THE ACTIVITY OF THE HAIR FOLLICLE 455 REFERENCES (1) A.M. Kligman J. Invest. Dermatol. 33 307 (1959). (2) R. J. Myers and J. B. Hamilton Ann. N.Y. Acad. Sci. 53 562 (1951). (3) A.M. Kligman A.M. A. Arch. Dermatol. 83 175 (1961). (4) J. H. Kim, F. Herrmann and M. B. Sulzberger J. Invest. Dermatol. 38 351 (1962). (5) E. Johnson J. Endocrinol. 16 337 (1958). (6) F. J. Ebling and E. Johnson Symposia of the Zoological Society of London 12 79 (1964). (7) T. H. Bissonnette Anat. Record 63 159 (1935). (8) N. E. Harvey and W. V. Macfarlane Australian J. Biol. Sci. 11 187 (1958). (9) A. Watson Proc. Zoological Society of London 141 823 (1963). (10) F. J. Ebling and E. Johnson ]. Embryol. Exptl. Morphol. 7 417 (1959). (11) F. J. Ebling and E. Johnson ]. Embryol. Exptl. Morphol. 9 285 (1961). (12) E. Johnson and F. J. Ebling In press. (13) E. H. Mercer Keratin and Keratinisation (1961) (Pergamon Press, Oxford). (14) F. J. Ebling and G. R. Hervey ]. Embryol. Ezptl. Morphol. 12 In press (1964). (15) E. Johnson ]. Endocrinol. 16 351 (1958). (16) M.P. Mohn in W. Montagna "The Biology of Hair Growth" Chapter 15 (1958) (Academic Press Inc., New York). (17) B. L. Baker and W. L. Whitaker Anat. Record 102 333 (1948). (18) H. J. Whiteley, ]. Endocrinol. 17 167 (1958). (19) E. Johnson J. Endocrinol. 16 360 (1958). (20) F. J. Ebling and E. Johnson ]. Endocrinol. 29 193 (1964). (21) Y. L. Lynfield ]. Invest. Dermatol. 35 323 (1960). (22) J. B. Brown Recent Progress in the Endocrinology of Reproduction 335 (1959) (Academic Press, New York). (23) T. H. Bissonnette and E. Wilson Science 89 418 (1939). (24) T. H. Bissonnette and E. E. Bailey Ann. N.Y. Acad. Sci. 45 221 (1944). (25) N. T. M. Yeares Australian J. Agric. Research 6 891 (1955). (26) E.G. Rennels and W. P. Callahan Anat. Record 135 21 (1959). (27) P. Flesch in S. Rothman "Physiology and Biochemistry of Skin", Chapter 26 (1953) (University Press, Chicago). (28) B. W. L. Brooksbank Physiol. Revs. 41 623 (1961). (29) E. J. Van Scott and T. M. Ekel J. Invest. Dermatol. 31 281 (1958). (30) M. Singh and J. McKenzie J. Anat. 95 569 (1961). (31) J. B. Hamilton Am. J. Anat. 71 451 (1942). (32) J. B. Hamilton J. Clin. Endrocinol. and Metabolism 20 1309 (1960). (33) E. J. Van Scott J. Invest. Dermatol. 31 35 (1958). (34) E. H. Mercer and M. S.C. Birbeck J. Biophys. Biochem. Cytol. 3 203, 215, 223 (1957). DISCUSSION DR. J. BLAKE: Could you distinguish between roles played by hormones vs. intercellular contact (34) in cell differentiation in the growth of hair? TuE L•CTUR•R: I do not know about distinguishing between the roles played by hormones and intercellular contact. I make a clear distinction between the effect of hormones on the initiation of follicular activity and on the growing hair. The initiation of follicular activity is affected by a number of hormonal states, whereas the rate of hair growth was, in our experiments, only clearly affected by oestrogens, which reduce the rate of hair growth. I do not know how they act they may inhibit cell division, but by analogy

JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS with their other effects on the epidermal derivatives, I would expect them to promote the catabolic phase, of which keratinization is part, at the expense of the anabolic phase of cell activity. Mercer et al (34) suggest that inter- cellular adhesion in the mid-bulb region is limited to small localized areas, but higher up the follicle there is a dense amorphous adhesive cement between the cells, and this cement is essential to keratinization. I would not care to speculate whether this process is a point where the oestrogen might act, but the question could be investigated experimentally. DR. E. LuDwiG: Are you able, on the basis of your observations on various animal species, to confirm that the hair follicle reacts to damage only in the following two ways: Firstly, by retiring in the telogen stage, in which instance a perfectly normal club hair results, and secondly, by disintegration in which case the result is a distrophic broken hair shed about 10 to 14 days after injury. THE LECTURER: In our studies we have not been able to bring about a disintegration of the follicle, but we have carried out a number of studies on the reaction of the follicle to plucking of the hair. It is well known that plucking of a hair in the telogen phase initiates a new cycle of activity. In the rat, if a hair is plucked when it is in the growing phase, the cycle appears to be shortened a premature catagen is induced, and this is consistent with your observation in man. The result appears to be evidence against the hypothesis that during the growing phase there is a build up of an inhibitor within the follicle if that hypothesis were true one would expect the follicle to produce a full-length hair after each plucking. I thus confirm your first point, but as to disintegration of the follicle--we have not observed it. MR. A. FOSTER: It has not been made clear whether the changes that take place in phasing are permanent or whether they only follow the next wave after the graft. Are they permanent with successive waves ? THE LECTURER: This question is slightly complicated. If the follicles are put out of phase by an operative procedure, such as grafting or plucking, they remain in this state for a long time. But it is possible that they gradually alter their phasing. Our animals have only a limited life so that it is difficult to give a categoric answer from our present evidence. MRS. H. BUTLER: I believe I understood you to say that adding oestrogen increased the rate of keratinization, but delayed the falling out of the hair. Could you clarify that please ? THE LECTURER: There are two quite different effects of oestrogens. One is the effect on the timing of the cycle itself in all our experiments it was clear that oestrogens both delay the initiation of follicular activity and the shedding of club hairs. Secondly, there is the effect on the growing hair. In female rats the hair is not quite as long as in males, but after removal of the