Journal of neurosurgery. Spine
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The authors studied the histological and immunohistochemical features of ossified posterior longitudinal ligament (PLL) of the cervical spine, especially in the calcification and ossification front. ⋯ The enchondral ossification process in the ossified PLL was closely associated with degenerative changes of elastic fibers and cartilaginous cartilage formation, together with the appearance of metaplastic hypertrophic cartilage cells and neovascularization. The authors also found that VEGF-positive metaplastic chondrocytes in the ossification front and different expression patterns of collagens probably play some role in the extension of the ossified PLL from the ossification front.