text: from a combination of MrgDCreERT2;Ai14, ThCreERT2;Ai14, and 
  CalcaCreERT2;Ai14 lines (mixed sex).3 One month after SNItrans, 
  animals were transcardially perfused with sterile saline followed by 
  a fixative containing 4% formaldehyde. Ipsilateral and contralateral 
  L4 DRG were removed and postfixed for 24 hours on a shaker at 
  room temperature before being washed in PBS and stored 
  at 280˚C in CI-VM1 (35% dimethyl sulfoxide, 35% ethylene glycol 
  in PBS) until clearing. Tissue clearing was then performed as 
  previously described.67 In brief, 
  the tissue was exposed to 
  a gradient of 1-propanol containing 0.3% triethylamine (30, 50, 
  75, 90, 95, 100, 100%) and washed in this solution at 37˚C for 
  24 hours. The tissue was then rehydrated in PBS and labelled with 
  primary antibodies for 1 week at 37˚C (mouse anti-TDP43 and 2x 
  anti-RFP, Table 2). The tissue was washed for 24 hours and 
  incubated with appropriate secondary antibodies (Table 2) for 
  another week at 37˚C. The tissue was subsequently washed for 
  24 hours, dehydrated again in increasing concentrations of 1- 
  propanol containing 0.3% triethylamine, and mounted in benzyl 
  alcohol with benzyl benzoate (1:2 ratio) containing 0.3% triethyl- 
  amine on glass slides with silicone spacers. 
  Imaging was 
  performed on an Olympus spinning disk confocal microscope at 
  20x, with 2-mm z-steps. The tissue was stored at 4˚C for 
  ;16 months before imaging, so only the tissue that remained 
  transparent at this time was used for downstream analyses. 
  Volumetric analyses were performed using Imaris using the “spots” 
  feature with region growth (to allow for different-sized spots), 
  background subtraction, and point spread function elongation 
  (standard 2 3 XY). Initial spot diameters were set based on 
  MrgDCreERT2;Ai14 nuclear size (as labelled by red fluorescent 
  protein (RFP)). Spot classification was then performed blind by 
  adjusting the quality threshold to balance detection in superficial 
  and deep tissue. This step was necessary due to differences in 
  tissue quality after long-term storage. Any labelled spots in the 
  adjacent nerve were then deleted (eg, labelled Schwann cells or 
  debris). Count and volumetric data were then exported for analysis 
  in R. Data were filtered for very small (,5 mm3) and very large 
  (.2000 mm3) spots to further remove any debris, labelled satellite 
  glia or doublets within the ganglia. In both cases, these filters were 
  approximate and did not exclude the possibility that some spots 
  correspond to either class in the final dataset. The upper limit of the 
  “small” DRG nuclei size category was defined as the upper bound 
  of 32 easily identifiable MrgD1 nuclei (258 mm3). The boundary 
  between “medium” and “large” bins (400 mm3) was less clearly 
  defined in the samples and was therefore set as the approximate 
  midpoint of the volume distribution. A combined size category for 
  all nuclei greater than 258 mm3 was also examined, and the results 
  mirrored those of “medium” and “large” bins. 