Ossification center.

MRI shows low signal intensity (black) in the central area of the vertebral body corresponding to an ossification center (upper arrow). Low signal intensity corresponding to an ossification center is also visible in the lateral area of the vertebral pedicles (lower arrow) (A). Microscopic transversal sections (4 μm) stained with hematoxylin-eosin of the central area of the vertebral body (B) and the lateral areas of the vertebral pedicles (C) show hematopoietic cells between the spiculae, indicating that the low-intensity areas visualized by MRI are hematopoietic areas. The upper and lower arrows in panel A correspond with the arrows in panels B and C, respectively. Original magnification × 40.