Lack of osteocytic pro-HSC signals and absence of spindle-shaped cells in mice with activation of the PTH1R in osteocytes. (A) Quantitative RT-PCR analysis comparing gene expression in bones from TG and WT mice pro-HSC signals: CXCL12, Ang-1, IL-7, IL-6, and VCAM-1. (B) H&E staining of longitudinal sections of representative femora and tibiae of 4- to 6-week-old WT, PTH-treated WT, and TG mice, as indicated. Black arrows point to the immature spindle-shaped osteoblastic cells. Magnification is 20×. Bars indicate 0.1 mm. (C) Immunohistochemistry using Nestin Abs of femur from 4- to 6-week-old WT, PTH-treated WT, and TG mice, as indicated. Arrows point to Nestin⁺ spindle-shaped immature osteoblasts, blue hematoxylin. Magnification is 40×. Bars indicate 0.05 mm. (D) Immunohistochemistry using Nestin Abs of tibia from 6-week-old WT, PTH-treated WT, and TG mice, as indicated. Arrows point to Nestin⁺ spindle-shaped immature osteoblasts, blue hematoxylin. Magnification is 60×. Bars indicate 0.05 mm.