Fig. 4.  Temporal sequence of intraspinal pathologic lesions in the lumbar spinal cord caused by two transient aortic cross-clamps (7.5 min) at 33°C. Representative cross-sections in series reveal time-dependent changes in neurons (A ), microglia/macrophages (B ), and reactive astrocytes (C ). Note the significant spinal cord atrophy at 21 days. All sections were sampled from the ∼L3–L4 spinal cord and were collected at the times indicated from a severely affected animal. An enlargement of the boxed regions is provided below each cross-section. Scale bar = 200 μm in low-magnification images and 100 μm in high-power images.