Hematologic features associated to fibrosis. White, gray, dark gray, and black histograms are JAK2^WT (n = 7) or JAK2^V617F virus-recipient mice displaying no (n = 4, days 52 to 98 after transplantation), low-grade (n = 5, days 161 to 235 after transplantation), and high-grade fibrosis (n = 4, days 131 to 143 after transplantation), respectively. Error bars indicate SE.