MRC1 and amyotrophic lateral sclerosis: To investigate the changes in PVM during ALS disease progression, we counted the number of PVM in the lumbar spinal cord of SOD1G93A mice at P60 (a pre-symptomatic stage), P120 (an early symptomatic stage), P140 (a late symptomatic stage), and P160 (an end-stage), by immunostaining for CD206 and CD31.