Figure 2. Gross phenotype and inflammatory skin phenotype of the Mpzl3 −/− mice.

(a) Gross phenotype of Mpzl3 +/+, +/− and −/− littermates at the ages indicated. Mice shown were in the C57BL/6 strain with black or albino coat colors. Mpzl3 −/− mice developed recurrent alopecia, and patches of regrown hair had vellus-like appearance (arrowhead). Mpzl3 −/− mice frequently had lower body weight than control littermates (the pairs at 5 and 9 months of age). (b–g) Development of inflammatory skin lesions in Mpzl3 −/− mice but not control littermates. Dilated blood vessels in the ear (b); redness of the muzzle, upper chest and anticubital areas (c, e); red, scaly eczematous lesions on the muzzle (c, e); periorbital swelling and hair loss (d, f), loss of most vibrissae (e–g), inflammatory lesions of the eye (f), and persistent ulceration in the upper chest (g). (h) The thickness of the ear in Mpzl3 +/− and −/− littermates. Bar=standard deviation, N=30 each, 1–8 months old. (i–n) H&E staining of lesional skin from Mpzl3 −/− mice (j, l, n) compared with location-matched skin from +/− littermates (i, k, m). Mpzl3 −/− skin showed epidermal hyperplasia (opposing arrows), hypergranulosis, hyperkeratosis and lymphocyte/monocyte infiltration, increased dermal thickness, dilated blood vessel in the ear (arrowhead) (j), sebaceous hypertrophy (l, n), ulcer in the upper chest area (n), with epidermal hyperplasia and parakeratosis in the wound edge (arrow) and diffuse leukocyte infiltration in the dermis (n). Scale bars = 100 μm (i, j), scale bars = 200 μm (k–n).