Hematopoietic progenitor colonies from ATF4^−/− 15.5-dpc embryos are smaller and reduced in number per fetal liver.

(A) In vitro differentiation of 15.5-dpc fetal-liver cells from wild-type (n = 18), ATF4^+/− (n = 19), and ATF4^−/− (n = 22) embryos. The number of CFU-E, BFU-E, CFU-GM, and CFU-GEMM colonies per fetal liver were all significantly reduced in ATF4^−/− embryos. There was no significant difference between the number of colonies in wild-type and ATF4^+/− embryos. (B) Hematopoietic progenitor colonies. BFU-E colonies were photographed on day 8 and CFU-GEMM colonies on day 10 of in vitro differentiation. Magnification 100 ×. (C) The number of cells per plate and per colony after 12 days of in vitro differentiation of 5 × 10⁴ nucleated 15.5-dpc fetal-liver cells. The average size of ATF4^−/−hematopoietic progenitors was significantly smaller than those from wild-type and ATF4^+/− embryos. There was no significant difference between the size of colonies from wild-type embryos and those from ATF4^+/− embryos.