Figure 6

Presence of cytokeratin 8 (CK8)-positive clusters in the nucleus pulposus (NP) of immature and mature bovine discs. Toluidine blue staining of the proximal caudal vertebral growth plates (arrowhead) of immature (a) and mature (b) spinal segments (VB = vertebral body). Immunofluorescence staining of CK8 performed on frozen NP tissue sections taken from the uppermost caudal disc of immature (c,d) and mature (e,f) bovine tissues. Tissue sections were also imaged under classical phase-contrast microscopy (PHASE), and nuclei were visualized with DAPI (4'-6-diamidino-2-phenylindole) (scale bar = 60 μm).