Figure 3

Volume correction demonstrated increased and localized pathology in aged rats compared to young at 28 dpi. Confirming observations in 3D reconstructions, stereological assessment of total spinal cord volume between T6 and T12 dorsal roots revealed a significant difference between age groups (Student’s t test, *p< 0.001) (A). Accordingly, lesion volume from Figure 3A was normalized to total cord volume (A) and expressed as a percentage. As such, aged rats showed a strong but non-significant trend for increased % lesion volume compared to young rats (Student’s t test, p= 0.056) (B). Stereologically analyzed coronal diagrams from a single section immediately caudal to the injury epicenter demonstrated potential differences in lesion area (red line) relative to cross-sectional area (black line) (C). When lesion area at each cross-section was normalized to total area at the same cross-section and quantified along the length of the spinal cord, a single point of significance was detected immediately caudal to the injury epicenter, where % lesion area of aged animals was significantly greater than the young (Student’s t test, *p< 0.05) (D). (E) Additionally, quantification of the % spared tissue along the length of the spinal cord demonstrated the same effect as % lesion area, confirming localized differences between age groups in pathology (Student’s t test, *p< 0.05). Data points represent individual animals and the horizontal line indicates group mean.