Figure 1.

Methodology for vertebral grading of development. By using microRad (A, B) and microCT (A,C) vertebrae were classified as being either immature (IMV) or mature with end plates (MV). The white arrows indicate differing images of endplates, representing MV (B, C), whereas the white arrowhead depicts a representative IMV on microCT (C). Histologic samples were graded as II, III, IV, or V, depending on the presence or absence of hypertrophic chondrocytes or bone in primary and secondary ossification centers (D); black boxes outline primary centers of ossification and ovals outline secondary centers of ossification, growth plates (GP) are bracketed, and intervertebral disc spaces (IVD) are labeled.