Reduced platelet (PLT) production in THPO-ASO–treated FBV/N mice. (A) THPO-ASO or saline (control) treatment scheme. WT female FBV/N (NIH Jackson–homozygous phosphodiesterase 6Brd1 mutant) mice received repeat injections of saline (controls) or nonconjugated THPO-ASO (50 mg/kg, SC) beginning on day 65 after birth. (B) Changes in mean platelet count over time in saline- (red line, n = 3) or THPO-ASO–treated (blue line, n = 7) mice. (C) Complete blood counts on day 135 after birth. (D) Plasma TPO levels on day 135 after birth. (E) Representative images of megakaryocytes (MKs) in the femoral bone marrow on day 135 after birth in saline- or THPO-ASO–treated mice. Megakaryocytes were visualized via anti-CD41 (GPIIb; green) and anti-VWF (red) antibodies. Nuclei were stained with Hoechst 33342 (blue). Original magnification ×20. Scale bars, 100 µm. (F) Quantitative evaluation of megakaryocyte density in the bone marrow on day 135 after birth. Numeric data are shown as mean ± standard error of the mean. The 2-tailed, unpaired Student t test was used for comparison of means. *P < .05. HCT, hematocrit; HGB, hemoglobin; MCH, mean corpuscular hemoglobin; MCHC, mean corpuscular hemoglobin concentration; MCV, mean corpuscular volume; MPV, mean platelet volume; NS, not significant; RBC, red blood cell; RDW, red blood cell distribution width; S.C., subcutaneous; WBC, white blood cell.