Morphologic differences of the vascular buds in the vertebral endplate: scanning electron microscopic study.

Study Design: Vascular buds in rabbit vertebral endplates were examined by scanning electron microscopy of corrosion casts.
Objectives: To examine morphologic differences between vascular buds in two regions of the vertebral endplate (inner anular and nucleus pulposar).
Summary of Background Data: Vascular buds are specific structures present at the vertebral endplate that are important as nourishing channels. There is a significant difference in permeability between the lateral portion (inner anular) and the central portion (nucleus pulposar) of the endplate, the latter usually being permeable and the former being impermeable. Morphologic differences between vascular buds in the two regions have not been investigated previously.
Methods: Eight 20-week-old rabbits were used. Vascular buds in rabbit vertebral endplates were examined by scanning electron microscopy of corrosion casts.
Results: The vascular buds in the region of the inner anulus form simple loops, but those in the area near the nucleus pulposus exhibit swollen and complex coil-like loops. Although they differ structurally, the average number of vascular buds per area does not vary between the two regions.
Conclusions: We suggest that the morphologic difference between the vascular buds in the two regions (inner anular and nucleus pulposar) plays a principal role in permeability at the endplate.