Figure 3.

Injured p1 and p5 IVDs heal near-regeneratively suggesting neonatal IVD regeneration does not recapitulate the AF lamellar structure after a severe herniation-type injury at any post-natal age

(A and B) Representative (A) ScxGFP and (B) DAPI images of AF controls and injury sites of p1 and p5 mice (biological n = 5/age) 56 days after injury.

(C and D) Quantification of (C) % cells expressing ScxGFP and (D) total number of cells within injury sites.

(E and F) Representative Picrosirius Red Alcian blue images of AF controls and injury sites of p1d56 and p5d56 mice under (E) brightfield and (F) polarized light.

(G and H) Quantification of (G) % repair tissue within the injury site and (H) collagen disorganization score. Scale bars = 100 μm. Quantifications are compared to p14 and p28 levels marked by light and dark blue dotted lines respectively. Outlines indicate injury sites (yellow/green) and repair tissue (white).

(I) Arrows point toward cellular repair tissue (white) and adjacent AF structure near injury sites (yellow) (I) Digital X-rays are used to calculate DHI in p1 injured and control IVDs. Scale bars represent 2.5 mm. Error bars = SD. Student’s t test with p < 0.05 determined significance, depicted in graphs as a horizontal black line.