Fig. 5. Development of dermal cysts in Hr^-/- skin. (A) Sagittal sections of Hr^-/- mouse skin at 3 months (3 mo), 6 months (6 mo) and 1 year (1 yr) stained with Hematoxylin-Eosin. Scale bar: 100 µm. (B) In situ hybridization with a sebaceous gland marker (SCD1). In situ hybridization of adjacent sagittal sections of backskin from adult (1 year) Hr^-/- mouse with Scd1-specific antisense (AS, left panel) or sense (S) probes (right panel). Arrowheads indicate positive signal in subset of cells surrounding cyst. Scale bar: 50 µm. (C) Lipids detected in dermal cysts. Oil red O staining on sagittal sections from backskin of adult (1 year) Hr^-/- mouse. Scale bar: 50 µm. (D) Immunohistochemical detection of keratinocyte differentiation markers. Positive staining in the cyst walls for K14 (green) and K17 (red) and both (K14/K17, yellow) in sagittal sections of backskin from adult (1 year) Hr^-/- mouse. Scale bar: 20 µm. (E) Cysts do not express epidermal or hair markers. Immunohistochemical detection of loricrin, filaggrin and trichohyalin in adult Hr^-/- backskin. Scale bar: 50 µm. (F) Proliferation in cyst wall colocalizes with K14. Immunofluorescent detection of BrdU (red) and K14 (green) in sagittal section of Hr^-/- mouse backskin (P45). DAPI, nuclear stain (blue). Scale bar: 20 µm.