Migration of melanoblasts into the developing murine hair follicle is accompanied by transient c-Kit expression.
Disruption of the c-Kit/stem cell factor (SCF) signaling pathway interferes with the survival, migration, and differentiation of melanocytes during generation of the hair follicle pigmentary unit. We examined c-Kit, SCF, and S100 (a marker for precursor melanocytic cells) expression, as well as melanoblast/melanocyte ultrastructure, in perinatal C57BL/6 mouse skin. Before the onset of hair bulb melanogenesis (i.e., stages 0-4 of hair follicle morphogenesis), strong c-Kit immunoreactivity (IR) was seen in selected non-melanogenic cells in the developing hair placode and hair plug. Many of these cells were S100-IR and were ultrastructurally identified as melanoblasts with migratory appearance. During the subsequent stages (5 and 6), increasingly dendritic c-Kit-IR cells successively invaded the hair bulb, while S100-IR gradually disappeared from these cells. Towards the completion of hair follicle morphogenesis (stages 7 and 8), several distinct follicular melanocytic cell populations could be defined and consisted broadly of (a) undifferentiated, non-pigmented c-Kit-negative melanoblasts in the outer root sheath and bulge and (b) highly differentiated melanocytes adjacent to the hair follicle dermal papilla above Auber's line. Widespread epithelial SCF-IR was seen throughout hair follicle morphogenesis. These findings suggest that melanoblasts express c-Kit as a prerequisite for migration into the SCF-supplying hair follicle epithelium. In addition, differentiated c-Kit-IR melanocytes target the bulb, while non-c-Kit-IR melanoblasts invade the outer root sheath and bulge in fully developed hair follicles.
Peters
Eva M J
EM
Department of Dermatology, University Hospital Eppendorf, University of Hamburg, Germany.
Tobin
Desmond J
DJ
Botchkareva
Natasha
N
Maurer
Marcus
M
Paus
Ralf
R
D000818:Animals; D000831:Animals, Newborn; D002465:Cell Movement; D018859:Hair Follicle / Q000196:embryology / Q000502:physiology* / Q000648:ultrastructure; D007150:Immunohistochemistry; D008544:Melanocytes / Q000378:metabolism / Q000502:physiology* / Q000648:ultrastructure; D051379:Mice; D008810:Mice, Inbred C57BL; D008854:Microscopy, Electron; D009024:Morphogenesis; D019089:Stem Cell Factor / Q000378:metabolism*; D013234:Stem Cells / Q000378:metabolism / Q000502:physiology / Q000648:ultrastructure
D019089:Stem Cell Factor