All mice with Apc haploinsufficiency develop a macrocytic anemia with monocytosis. (A) CBC of Apc^del/+and Apc^fl/+mice alone or crossed with Egr1^+/−(E), or Tp53^+/− (P), or Egr1^+/−, Tp53^+/− (EP) are shown. CBCs of Apc^del/+ mice were taken at the time of sacrifice, when the mice were severely anemic and moribund. Blood counts of Apc^fl/+ control mice were taken during a similar timeframe, but mice were not moribund. (B) Representative peripheral blood smears (×1000) and spleen sections at ×40 and ×500 from anemic Apc^del/+mice alone or crossed and of Apc^fl/+ control mice. Images were obtained using an Olympus microscope (Model BX51), equipped with an Optronics 3CCD 1080p digital camera, and processed with Adobe Photoshop. MO, monocytes; NE, neutrophils; PLT, platelets; WBC, white blood cells.