Figure 1.

Pfirrmann grade III with normal height (NH) is the key stage of IVDD with the highest autophagy in NP cells. (a) Representative plain scanning and NP signal intensity of MRI of grades I, III(NH), and V according to the Pfirrmann classification. (b) The reconstructed 3D colour images of various stages of IVDD. (c) HE staining and immunohistochemistry analysis of collagen II and aggrecan in human NP tissues from the grade I, III(NH), and V groups. Arrows indicate positive cells. The values are shown as the mean ± standard deviation (S.D.) of three independent experiments performed in triplicate. ^∗P < 0.05, ^∗∗P < 0.01. NH: normal height.