Purpose: This review evaluates the effects of γ-rays on the regeneration of murine hair follicles in the natural hair cycle. A series of studies were performed to investigate this issue, in which the whole bodies of C57BL/10JHir mice in the 1st telogen phase of the hair cycle were irradiated with γ-rays.
Results: The dermis of the irradiated skin showed a decrease in hair follicle density and induction of curved hair follicles along with the presence of white hairs and hypopigmented hair bulbs in the 2nd and 3rd anagen phases. An increased frequency of hypopigmented hair bulbs was still observed in the later hair cycle at postnatal day 200. There was no significant difference in the number of stem cells in the hair bulge region between control and irradiated skin.
Conclusions: These results show that the effects of γ-rays on the pigmentation of murine hair follicles are persistently carried over to later hair cycles, although those on the number and structure of hair follicles appear to be hidden by the effects of aging. Our findings may be important for understanding the mechanisms of the actions of stem cells on hair regeneration in connection with age-related phenotypes. 相似文献
AbstractPurpose: The purpose of this study was to determine whether the effects of gamma rays on the regeneration of hair follicles are carried over to later hair cycles.Materials and methods: The whole bodies of C57BL/10JHir mice in the 1st telogen phase were irradiated with 60Co γ-rays. Mice were examined for the effects on hair follicles, including their number, morphology and pigmentation in the 3rd anagen phase. Effects of γ-rays on hair follicle stem cells were investigated by the indirect immunolabeling of keratin 15 (K15).Results: Decreased hair follicle density and induction of curved hair follicles were observed in the dermis of irradiated skin. In addition, white hair and hypopigmented hair bulbs were found. The number of K15-positive hair follicle stem cells in the hair bulge region of irradiated skin appeared to decrease slightly but not significantly.Conclusions: These results suggest that the effects of γ-rays are carried over to a later hair cycle to affect the number, structure and pigmentation of hair follicles in the 3rd anagen phase when stem cells and committed progenitors for keratinocytes and melanocytes are irradiated in the 1st telogen phase. 相似文献
Abstract The hair cycling pattern differs between humans and mice: for the former it is mosaic, while the latter show a wave pattern.
We focused on the presence or absence of synchronization of the hair cycle based on the distribution of Merkel cells. The
three-dimensional distribution and number of Merkel cells in the skin at various sites were determined in guinea pigs and
rats. Using ethylenediaminetetraacetic acid, various types of hair follicles were obtained from the facial, abdominal, nipple,
back, tail, perianal and plantar skin. Epidermal sheets containing numerous hair follicles were immunostained using monoclonal
murine antibody CK20 which is generally accepted to be a specific immunocytochemical marker for Merkel cells of various species.
Merkel cells were absent in the trunk skin of guinea pigs and rats, in complete contrast to the situation in humans. In vibrissa
and other hair follicles within specialized sensitive areas, Merkel cells were found in varying numbers. Some differences
in their distribution and number were observed between guinea pigs and rats. The absence of Merkel cells in the hair follicles
of the trunk skin of rats and guinea pigs implies that Merkel cells are not essential for the induction and promotion of hair
growth but have some different functional significance in hair follicles.
Received: 7 April 1999 / Revised: 8 June 1999 / Accepted: 8 October 1999 相似文献
The distribution of Merkel cells in human fetal hair follicles was studied using whole mounts of separated epidermis with attached hair follicles. The technique had the advantage of enabling the elucidation of the spatial relationships of Merkel cells with other cells in the skin. In a 16-week-old fetus the hair anlagen had formed one or two epithelial swellings of variable size. In a 17-week-old fetus sebaceous glands and the bulge of the hair follicle were recognizable and immunoreactive Merkel cells were present in the bulge and surrounding the acrotrichium (intraepidermal follicular canal). In a 20-week-old fetus the sebaceous gland and bulge were well formed and immunoreactive Merkel cells were concentrated in the bulge and infundibulum. In vertical sections of a 20-week-old fetus immunoreactive Merkel cells were also situated in the vicinity of the bulge. Arrector pili muscles were first observable in a 24-week-old fetus being weakly stained with anti-desmin antibody. In a 24-week-old fetus, nerves were also stained within the arrector pili muscles with S-100 protein antibody. In the presumptive arrector pili muscle immunoreactivity for S-100 protein developed before or at the same time as immunoreactivity for desmin. Merkel cells or their products in the bulge may serve as attractants for the growing arrector pili muscle which contain peripheral nerves. Following our report that dermal Merkel cells influence the formation of the dermal nerve plexus, perifollicular Merkel cells near the bulge may also play an inductive and growth-stimulative role for the perifollicular nerve plexus. 相似文献