Histologic study of the regeneration process of human hair follicles grafted onto SCID mice after bulb amputation.
This study examines histologically the degeneration and subsequent regeneration processes of human hair follicles whose bulb is severely damaged. Human scalp hair follicles were isolated and grafted onto immunodeficient mice after their bulb was amputated. On day 14, thickening and corrugation of the vitreous membrane, apoptosis of follicular keratinocytes, and regression of the lower portion of the follicles were observed. By day 20, mesenchymal cells had accumulated around the lower end of the follicles. From day 14 through 50, the follicular regression and apoptosis continued, and between days 30 and 40 the follicles became maximally shortened, and the vitreous membrane disappeared. By day 50 the lower end of the follicles had become cup-shaped, and the cup surrounded an aggregate of mesenchymal cells that corresponded to the dermal papilla. By day 60, all the grafted follicles had developed into anagen VI follicles, and the apoptosis had ceased. These results indicate that human scalp hair follicles whose bulb is completely destroyed enter into dystrophic telogen after restoration of the dermal papilla, then into anagen, and that the duration of the dystrophic telogen is shorter than that of the normal hair cycle.
Hashimoto
T
T
Department of Dermatology, Niigata University School of Medicine, Japan.
Kazama
T
T
Ito
M
M
Urano
K
K
Katakai
Y
Y
Yamaguchi
N
N
Ueyama
Y
Y
D000818:Animals; D017209:Apoptosis; D018859:Hair Follicle / Q000293:injuries* / Q000473:pathology / Q000503:physiopathology* / Q000637:transplantation; D006801:Humans; D015603:Keratinocytes / Q000473:pathology / Q000502:physiology; D051379:Mice; D016513:Mice, SCID; D012038:Regeneration / Q000502:physiology*; D013997:Time Factors; D014183:Transplantation, Heterologous; D014947:Wounds and Injuries / Q000473:pathology* / Q000503:physiopathology*