Photomicrographs of periodic acid Schiff-stained 4-μm sections of wing membrane prepared as previously described from a little brown bat ( Myotis lucifugus ) infected by Geomyces destructans. (a) Fungal hyphae penetrate and replace apocrine gland (white arrow), hair follicle (black arrow pointing to hair shaft), and sebaceous gland (arrowhead). (b) Normal pilosebaceous unit including the apocrine gland (white arrow), hair follicle (black arrow pointing to hair shaft) and sebaceous gland (arrowhead). (c) Infarcted region of wing membrane showing loss of all identifiable vital structures in the dermis, including blood vessels, connective tissue, muscle, elastin fibers and the large bands of connective tissue that traverse and stabilize wing membrane (arrow). No discernable cell structures or nuclei remain, the wing membrane is contracted and hypereosinophilic (intense red staining), and only residual pigment is present on the membrane surface (arrowhead). (d) Microscopic section of normal wing membrane with identifiable blood vessel containing circulating red blood cells (arrow) and nuclei of connective tissue cells (arrowheads).