Hair loss phenotype of conditional Dsc3 null ((a), (b), (c), (d)) and conventional Dsg3 null mice ((e), (f), (g), (h)). Both mouse lines show cyclic hair loss beginning around the time of weaning when the hair follicles on the back of the head enter telogen, the resting phase of the hair growth cycle. (a) Hair loss of a 56-day-old conditional Dsc3 null mouse and (b) a 53-day-old Dsg3 null mouse. (b and f) Acantholysis between the two cell layers surrounding the telogen hair club leads to loss of the hair shaft. Arrows indicate separation of the two cell layers. Note that early lesions are shown, that is, before the hair shaft is actually lost. (c and g) Telogen hairs with a single epithelial cell layer surrounding the club hair (brackets, nuclei of the epithelial sheet surrounding the clubs are stained in dark (c) and light (g) blue, resp.). In both cases, hair loss leads to the development of dermal cysts ((d and h); stars). Note that the hair loss in both mouse lines appears to follow the same mechanism, that is, loss of cell-cell adhesion between the two epithelial cell layers which anchor the telogen hair in the skin.
