Neonatal calvarial bone has been widely used for investigating the biological behaviour of intramembranous bones. This work evaluated the bone formation of neonatal calvarial bone by microcomputed tomography (micro-CT) and histomorphometry. Moreover, the viability of neonatal calvarial bone and the effect of micro-CT radiation exposure on neonatal calvarial bone viability were investigated. The calvarial bones of 4-day-old CD-1 mice were cultured in Dulbecco's modified Eagle’s medium (DMEM) or osteogenic medium (OM) for 23 days. Micro-CT scanning and histological analysis were performed on days 2, 9, 16 and 23. An “OM-control” group was scanned only on days 2 and 23 to evaluate the effect of a single micro-CT radiation dose on calvarial bones. Histomorphometric measurements revealed that the number of osteoblasts per unit bone surface area (N. Ob/BS, /mm²) (days 9, 16 and 23) and the number of osteoclasts per unit bone surface area (N. Oc/BS, /mm²) (days 9 and 16) were higher and lower, respectively, in the OM group than in the DMEM group. Moreover, the calvarial bone survived for at least 16 days in vitro, as indicated by tartrate-resistant acid phosphatase (TRAP)-positive staining. Micro-CT assessment revealed that the bone surface (BS), bone volume (BV), bone surface density (BS/TV(Tissue volume)) and percent bone volume (BV/TV) were greater in the OM group than in the DMEM group except at baseline on day 2. All bone parameters of calvariae cultured in OM and OM-control conditions were not significantly different on days 2 and 23. Thus, the radiation dose from micro-CT in our study design had no perceptible effect on the formation of mouse calvarial bone in vitro.

新生儿颅骨已被广泛用于研究膜内骨的生物学行为。这项工作通过显微计算机断层扫描 (micro-CT) 和组织形态测量评估了新生儿颅骨的骨形成。此外，还研究了新生儿颅骨的活力和显微 CT 辐射暴露对新生儿颅骨活力的影响。4 天大的 CD-1 小鼠的颅骨在 Dulbecco 改良的 Eagle 培养基 (DMEM) 或成骨培养基 (OM) 中培养 23 天。在第 2、9、16 和 23 天进行显微 CT 扫描和组织学分析。仅在第 2 天和第 23 天扫描“OM 对照组”以评估单个微 CT 辐射剂量对颅骨的影响。组织形态测量显示每单位骨表面积的成骨细胞数量（N.² )（第 9、16 和 23 天）和每单位骨表面积的破骨细胞数量（N.Oc/BS，/mm ²)（第 9 天和第 16 天）在 OM 组中分别高于和低于 DMEM 组。此外，如抗酒石酸酸性磷酸酶 (TRAP) 阳性染色所示，颅骨在体外至少存活了 16 天。Micro-CT 评估显示，OM 组的骨表面 (BS)、骨体积 (BV)、骨表面密度 (BS/TV(组织体积)) 和骨体积百分比 (BV/TV) 大于 DMEM除了第 2 天的基线。在第 2 天和第 23 天，在 OM 和 OM 对照条件下培养的颅盖骨的所有骨参数没有显着差异。因此，我们研究设计中来自微 CT 的辐射剂量对体外小鼠颅骨的形成。