BM and spleen features show evolution of the disease to myelofibrosis for all CALRdel52 mice and 1 CALRins5 mouse. (A) Spleen weight and (B) BM cellularity (n = 3-5), expressed as mean ± SEM. Student t test: *P < .05, **P < .001. (C) Hematoxylin-eosin-safran (HES), von Willebrand factor staining (vWF) and reticulin silver stain (RET) of 10-month-old mouse BM and spleen of CALRdel52 mice show clusters of MKs, osteosclerosis, and a progressive thickening of the reticulin network. Images were obtained using a DM2000 Leica microscope and a DFC300FX Leica camera with Leica Application Suite, v.2.5, OR1 acquisition software (×2.5 and ×25 magnifications).