Immunohistochemical labeling of nude mouse skin.

<p>The B6.Cg-<i>Foxn1^nu</i> nude mouse, like most mutant mice with alopecia, has mildly hyperplastic epidermis as seen in routine H&E stained sections (A, H). Terminal differentiation proteins (KRT1, B, I; and 10, C, J) are diffusely expressed above the stratum basale and below the stratum corneum. Keratin 6A (KRT6A) is normally expressed in the companion layer of the hair follicle but will be expressed higher in the follicle and in the epidermis during hyperplastic changes (D, K). Keratin 14 (E, L) and keratin 5 (F, M) label the basal cells. Keratin 14 is often more diffusely expressed as is the case here due to the mild acanthosis in nude mouse skin. Proliferating cells, as indicated by Ki67 labeling, is normally limited to the basal cells of the epidermis, outer root sheath of the hair follicle, and especially in anagen hair bulbs (G, N).