Bone marrow histology of a patient before (week 0) and at the end ofmirabegron treatment (week 24). Upper panel,reticulin fibers are stained black by silver impregnation (Gomori). Lower panel, immunohistochemistry staining with antibodies against humannestin protein (brown staining). Note decrease inreticulin fibrosis and increase innestin+ cells after 24 weeks of treatment. Magnification: 200x.