Figure 1
Differential expression of PAX1/9 and SOX9/5/6 in the intervertebral disc. (a–h) Sagittal sections of the thoracic vertebrae of a mouse embryo at E13.5 were processed for toluidine blue staining (a) and immunostaining for PAX1 (b,d,e–h), PAX9 (c,d), SOX5 (e), SOX6 (f), SOX9 (g), or ACAN (h). Red arrowheads in (a–h) indicate the IM that is positive for PAX1. (i–k) Cross sections of the thoracic IVD of a mouse embryo at E14.5 were processed for toluidine blue staining (i) or in situ hybridization for Pax1 (j) and Acan (k). Black arrowheads in (i–k) indicate the OAF of the IVD. (l–s) Sagittal sections of the thoracic vertebrae of a mouse embryo at E16.5 were processed for toluidine blue staining (l,m); immunostaining for PAX1 (n), PAX9 (o), SOX5 (p), SOX6 (q), or SOX9 (r); and in situ hybridization for Acan (s). The boxed region in (l) is shown at a higher magnification in (m). Panels shown in (n–s) correspond to the area of (m). Dotted line in (m–s) encloses the OAF. Ventral is to the right in (a–h,l–s) or the bottom in (i–k). Ca, cartilage; IAF, inner annulus fibrosus; IM, intervertebral mesenchyme; Nc, notochord; NP, nucleus pulposus; OAF, outer annulus fibrosus; VB, vertebral body. Scale bars, 100 μm.
