This cell was annotated manually using canonical skeletal muscle cell markers in the field (TRDN, TTN, NEB, DES, ACTN2). These cells expressed markers of both fast and slow twitch markers (MYBPC2, CPM, SORBS2, ATP2A2) hence designated as "transitional"
Lineage annotations were determined by Louvain clustering at resolution 0.1. Each lineage (fibroblast, muscle, immune, stromal) was then subsetted and reclustered. Final annotation resolution was chosen according to expression of biological markers; smaller clusters were combined were appropriate