Identification of major hematopoietic cell lineages from the liver and spleen by FACS light-scatter characteristics, fluorescence, and staining. FACS and H&E staining are presented for (A) axolotl blood, (B) liver, and (C) spleen. The CMV:GFP transgene expresses in all tissue types, but not in every cell. Depending on cell lineage, GFP expression can vary from 10% to 90% of individual cells. This is similar to the variable transgene expression seen in the equivalent transgenic mouse.³¹  All erythrocytes are GFP⁻ (red). Mature myeloid cell enriched populations are GFP⁺SSC^hi (blue). Lymphocyte enriched populations are GFP⁺SSC^lo (blue). The liver contains almost even numbers of myeloid cells and lymphoblasts. The spleen contains more lymphoblasts than myeloid cells. Black cells are excluded debris. (D) Cytospins followed by Wright-Giemsa, Alcian blue, α-naphthyl acetate esterase, and myeloperoxidase staining were performed to confirm cell morphology and characteristics. Scale bar: 20 µm (applies to the 8 individual cells stained with Wright-Giemsa). Blood composition was 3.7 ± 2.5% lymphoblastic cells, 1.3 ± 0.5% mature myeloid cells, and 95 ± 1.6% erythrocytes. Following removal of adipocytes, the liver was composed of 3.7 ± 0.6% lymphoblastic cells, 5.3 ± 1.5% mature myeloid cells, and 68.5 ± 10.2% erythrocytes (N = 3; Figure 1A). In comparison, the spleen contained 31.3 ± 12% lymphoblastic cells, 5 ± 0.8% mature myeloid cells, and 60.7 ± 15.5% erythrocytes (N = 3).