Herman B. Chase

THE GROWTH OF HAIR FOLLICLES IN WAVES

Waves of hair growth occur in several mammals, such as the mouse, rat, hamster, chinchilla, and rabbit, but do not occur as regular features in some other mammals: for example, the guinea pig and man. A wave may be defined as an orderly progression in time and space of follicles entering the growth phase, that is, anagen, of their cycles. A nonwave situation exists either when all follicles enter into activity simultaneously or, conversely, when follicles enter into this phase individually and without any synchronism or relationship with neighboring follicles. The mosaic type of hair replacement in the guinea pig is an example of the latter situation (Chase, 1954), each follicle proceeding through its growth cycle generations independently and with its own frequency. The presence of a wave, that is, the orderly spreading of the skin area containing follicular activity, indicates a correlation of follicles, due either to a common and spreading initiator acting on the follicles or to an action by some means of growing follicles on their resting neighbors. Synchronism of activity can also occur without the phenomenon of a wave, as in nonspreading islands of hair growth in older mice, indicating the correlation and interdependence of follicles, but an increasing refractoriness or inability of resting follicles to respond to the presence of their growing neighbors. The wave phenomenon is then an intermediate situation between the presence of an island of simultaneous activity and the occurrence of simultaneous activity over the whole animal. The rapidity of a wave is a reflection of the number of resting follicles ahead of the advancing edge that become active per unit time. An area of activity may have part of its periphery extending rapidly and another part not advancing a t all. Two waves, especially from opposite sides, may coalesce and then proceed anteriorly or posteriorly, or both. Some areas remain quiescent (lag areas), that is, do not become involved in a wave, for one generation, but may be responsive and participate a t the time of the next hair generation wave. Reported in this paper will be the observations on the repeated spontaneous hair growth waves in colored male and female mice of different strains, ages, and physiological conditions. The complete pelage was kept carefully clipped with electric clippers, the progress of waves being observed by the presence of color due to active hair bulbs in the skin. The outlines of these areas were drawn a t intervals of two days or less. Also reported and summarized in this paper will be the results of inducing hair growth by the plucking of resting hairs from different areas a t different ages and the plucking of areas of different sizes. A total of 230 mice of strains C57 BL, C57 BR, DBA, and C3H were observed * The work described in this paper was supported in part by Grant-in-Aid C-592 from the National Cancer Institute, Public Health Service, Bethesda, Md.; by Contract AT (30-1)2018 from the United States Atomic Energy Commission, Washington, D. C.; and by Contract 4 F 29 (600)-14?6 from the United States Air Force, Washington, D. C.

Relation of Hair Proliferation to Damage Induced in the Mouse Skin

Conclusions The combined treatment of methylcholanthrene-in-benzene painting plus 1000 r irradiation results in changes in the epidermis which are more severe than those occurring after either treatment alone. Sebaceous glands are destroyed by methylcholanthrene and redifferentiate only when hair growth is active. Where hair development is arrested or delayed by the irradiation, there is a failure of new sebaceous glands to redifferentiate until hair development again occurs. Furthermore, the initial damage to the epidermis in terms of hyperplasias and hyperkeratoses is less in areas where hairs were in anagen IV at the time of the single or combined treatment. Maximal damage occurs in telogen areas. Not only, then, is active hair proliferation associated with restoration, as in the case of sebaceous glands, but it also protects the epidermis from damage and it is associated with the repair of epidermal damage. The explanation of such phenomena is as yet incompletely known. Cells of the external sheath of the follicle are directly involved in redifferentiation of sebaceous glands and to a considerable extent in repair of the epidermis. This layer of external sheath cells forms the morphological continuity between the hair germ or bulb and the basal layer of the epidermis. The resistance of epidermis to damage, as well as the capacity for repair, which are associated with hair proliferation may well indicate a comparable functional continuity of the external sheath. In any case, the importance of considering and controlling conditions in the skin at the time of and after treatments is obvious.

Melanocyte precursor cells in the hair follicle germ during the dormant stage (telogen)

Der Ursprung der Melanozyten, die in der Haarwurzel während jedes Haarzyklus erscheinen, ist bisher unbekannt gewesen. Helle dendritische Zellen im ruhenden Haarkeim, welche an der Haarpapilla liegen, die sich während der frühen Anagen teilen und während Anagen III–IV Farbkörperchen hervorbringen, sind augenscheinlich die Vorläufer der Haarmelanozyten.

Effect of microbial antigens on irradiation mortality in mice.

Summary Mortality is reduced by approximately 50% in mice injected with zymosan (1000 γ) or with thermostable antigens from Proteus morganii, Klebsiella pneumoniae, or Escherichia coli. Soluble antigens from Gram-positive organisms, however, are ineffective. The greatest reduction of mortality is obtained by means of a Typhoid-Paratyphoid vaccine.

Effect of Diet on Obesity of Yellow Mice in Inbred Lines.

Summary and conclusions 1. The observation has been confirmed that yellow mice on continued inbreeding no longer become obese if maintained under the usual laboratory conditions. 2. Feeding a diet of the “synthetic” type made it possible to induce obesity in the yellow mice but not in their non—yellow litter—mates. 3. The obese yellow mice were observed to have fatty livers. Two of these animals were found to have liver tumors.

Radiation Depigmentation of Mouse Hair: Split-Dose Experiments and Melanocyte Precursors (Amelanotic Melanoblasts) in the Resting Hair Follicle

A study has been made of the depigmentation response of resting hair follicle melanoblasts to x-rays. The survival curve for these cells extrapolates to a value of about 6 and the D0 value is about 200 rads. Three days after initiating hair growth the physiological state of the cells has altered and the survival curve shows an increase in the D0 and

Glycogen in Skin of the Mouse During Cycles of Hair Growth

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The Use of Elongate Microbeams of X-Rays for Simulating the Effects of Cosmic Rays on Tissues: A Study of Wound Healing and Hair Follicle Regeneration'

. This is accompanied by a probable increase in cell number. Split-dose experiments with cells believed to be in G0 show a recovery factor of about 6 and a recovery curve which reaches a plateau at this value after time intervals of 6 hours or more. These results are obtained when the experiments are scored in the second postirradiation growth phase. The survival curve obtained when variable second doses are delivered 8 hours after a priming dose of 500 rads shows the same D0 value as the single dose curve but extrapolates to about 2.7. These data can be taken to indicate that there are not more than two melanoblasts in the resting zigzag hair fol...

Response of X-Irradiated Mice to Intravenous Inoculation of Intestinal Bacteria.

Summary During telogen, anagen I, and anagen II no glycogen is present in the hair follicle except for occasional granules in the capsule. Glycogen begins to appear in the lower external sheath in anagen III and persists in large quantities in this layer during the period of hair production. In addition, glycogen is found in the unkeratinized cuticle of the hair shaft and medulla in anagen IV through VI. Glycogen disappears abruptly from all these structures during catagen. Skin has 2 to 3 times as much glycogen during periods of hair growth than it has during telogen or at three days after plucking (anagen stages preceding hair growth). Cytochemical data indicate that this increase is due largely to the increased amount of glycogen found in the external sheath during periods of active hair production.

Anomalous Greying Effect in Mice with Higher Doses of X-rays

In a comparative biological study, mice were irradiated with a microbeam of x rays, 150 microns wide, and with a control macrobeam, 5 mm in diameter. At 9 days after irradiation, the microlesions contained visibiy damaged hair follicles, which were neither hypertrophied nor hyperplastic. After 18 days of healing, the surviving hair follicles in the microlesions were thin, disorganized columns of epithelial cells. In contrast, many surviving hair follicles in the large irradiated areas were hypertrophied and hyperplastic, and they often contained keratogenous cysts. The divergent results suggest that the healing of microlesions is unusually rapid and differs qualitatively from that observed in large lesions. The possible reasons for the differences are discussed in relation to the problems of radiation damage caused by heavy cosmic-ray primaries, grid irradation, and interface effects at the borders of large irradiated areas. The results indicate that the entire healing process should be studied separately in large and small lesions so that qualitative as well as quantitative differences in injury and repair can be properly evaluated. (P.C.H.)