(A–B). Single-cell suspensions of whole tissue isolates from injured ears at D5 subjected to flow cytometry using CD11b show two distinct populations of cells, one CD11b- and one CD11b+ (red boxes) in Acomys (A) and Mus (B). (C) Quantifying cells over time using flow cytometry shows a peak increase of CD11b+ cells in Mus at D3 and a broader but smaller peak of CD11b+ cells in Acomys between D3 and 5 (two-way ANOVA main effect time F = 31.86, p<0.0001, main effect species, F = 17.02, p=0.0002, *Sidak's multiple comparison test p<0.05, n = 4 animals combined left and right ear/species per timepoint). (D) Representative images of immunohistochemistry for myeloperoxidase (brown) in M. musculus (top panel) and A. cahirinus (bottom panel) 24 hr post injury. Nuclei (blue) were counterstained with Mayer’s Hematoxylin. Magnification 200x, Scale bars = 50 μm. Inset images highlight polymorphonuclear appearance of positively stained cells (red arrows). Scale bars = 20 μm. (E) Cell counts of polymorphonuclear/MPO+ cells in healing tissue per field of view (FOV) (n = 5 animals/species, D1; n = 6 animals/species, D3, D5; n = 4 animals/species, D10, two-way ANOVA, main effect time and species F = 11.12, p<0.0001, F = 8.229, p=0.007 respectively, *p<0.05 Sidak’s multiple comparisons test at time points indicated). (F) Myeloid protein IBA1 (red) reactivity in Acomys ear tissue at D5 showing distinct positive cells (yellow arrow) and negative cells with multi-lobed nuclei characteristic of neutrophils (green arrows). DAPI = grey, IBA1 = red. (G) Quantification of the total IBA1+ area in Acomys and Mus ears at D5, D10 and D20 normalized to total DAPI+ area (n = 3/species, two-way ANOVA, main effect time and species F = 0.132, p=0.723, F = 0.438, p=0.655, respectively) (H–K) Representative images of the IBA-1+ area quantified in (G) at D15. IBA-1+ cells localize proximal and distal to the injury site in Acomys and Mus and within the blastema in Acomys. IBA-1 = red, DAPI = grey, autofluorescent red blood cells (RBC) = orange. Scale bars (H,J) = 100 μm. Scale bar (I,K) = 50 μm Distal = left, Dorsal = top of image.