A hypothesis on the cause of chronic epidermal hyperproliferation in asebia mice

Summary We compared the skin of the mutant mouse asebia (ab/ab) with that of normal BALB/c mice by examining dermal cell counts, epidermal thickness, epidermal cell labelling index and ultrastructure. In asebia we found epidermal hyperproliferation and dermal inflammation, with much cell debris in the dermis. The very numerous macrophages, both intact and disintegrating, contained electron‐lucent crystals, apparently composed of lipid. We hypothesize that these crystals cause macrophage lysis followed by dermal inflammation and finally hyperproliferation in the overlying epidermis.