Fig. 10

Hematoxylin/eosin (a, b, d, e, g, h, j and k) and Safranin O (c, f, i and l) staining of the annulus fibrosus (AF) and nucleus pulposus (NP) 6 months after surgery. Intact AF displayed a normal pattern of fibrocartilage lamellas with rich proteoglycans, as shown by strong Safranin O staining (a, c). The NP exhibited clusters of large, vacuolated cells (b). A collapsed, wavy appearance with less safranin O staining was evident at the puncture site (d, f). No vacuolated cells were detected in the NP, with increasingly chondrocyte-like cells (e). Annular defect was filled in extensive fibrocartilaginous tissue with rich proteoglycans; a distinct border was discernible between the filled tissue and the native annulus (g, i). The NP exhibited fewer chondrocyte-like cells (h). Clusters of new connective tissue were formed in original defects with small amounts of undegraded PLGA material. The proteoglycan content was markedly reduced in the repair tissue, except for a strongly safranin O stained region at the sites of cartilaginous tissue (j, l). The NP showed a slight proliferation of chondrocyte-like cells (k). White arrows indicate the undegraded PLGA; white circle with dashed line indicates the site of fibrocartilaginous tissue