CD98hcΔ/Δmouse is embryonic lethal between E7.5 and E9.5. A. Pregnant uteri from heterozygous (CD98hcΔ/+) intercrosses were dissected at E12.5, E9.5 and E7.5. Some of the implantation sites were apparently smaller at E12.5 and E9.5. These smaller implantation sites were filled with blood clots (indicated by arrows) and appeared to lack embryonic component. In contrast, all the implantation sites were similar in size and contained embryonic component at E7.5, suggesting that CD98hcΔ/Δ is embryonic lethal between E7.5 and E9.5. B and C. β-galactosidase activity was visualized by X-gal staining to localize ΔCD98hc-β geo fusion protein in CD98hcΔ/+ embryo at E12.5 (B), either CD98hcΔ/+ or CD98hcΔ/Δ embryo at E7.5 (C, upper panel), and CD98hc+/+ embryo at E7.5 (C, lower panel). At E12.5, the expression Of ΔCD98hc-β geo fusion protein was most prominent in neuronal tissue, and weaker expression was also observed in lung and intestine. At E7.5, prominent expression of ΔCD98hc-β geo fusion protein was observed in the embryonic compartment of the CD98hcΔ/+ or CD98hcΔ/Δ embryo, but not in the CD98hc+/+ embryo.