Fig. 4. KSR immunohistochemical staining of mouse embryos. A, longitudinal section of E6.5 embryo in decidua stained with the KSR antibody. A, amnion; AC, amniotic cavity; E, embryonic ectoderm; M, embryonic mesoderm; En, embryonic endoderm. Staining is detected throughout the embryonic and extraembryonic tissues. Bar, 100 µm. B, whole mount KSR immunostaining of E10.5 embryo. Bar, 500 µm. C, KSR immunostaining of longitudinal section of E10.5 embryo. B, brain; FL, forelimb; H, heart; T, tail. Bar, 500 µm. D, KSR immunostaining of longitudinal section of E10.5 embryo. The section was coincubated with the primary antibody and the blocking peptide. Bar, 500 µm.