Fig. 8. Early expression of novel RA-generating activities in the neural tube and heart. Staining for RARE-lacZ expression is shown for Raldh2–/– and wild-type embryos treated with only two doses of RA at E6.75 and E7.25 (A-H) or three doses of RA at E6.75, E7.25 and E7.75 (I-L). For the E7.25 rescue: (A) E8.5 embryo shown 30 hours after the last dose; (B) E9.25 embryo shown 48 hours after the last dose; dorsal view of rescued Raldh2–/– embryo at E8.5 (C) and wild-type embryo (D). (E-G) Frontal sections through the hindbrain at E9.25; (H) transverse section through the spinal cord of an E9.25 rescued embryo. For the E7.75 rescue: (I) E9.25 embryo shown 36 hours after the last dose and (J) E10.25 embryo shown 60 hours after the last dose; also shown are higher magnification views at E9.25 of the heart for rescued Raldh2–/– embryo (K) and wild-type embryo (L). a, atrium, c, conotruncus; fp, floorplate; h, hindbrain; he, heart; ot, otic vesicle; r4/5, rhombomere 4/5 boundary; s, somite; sc, spinal cord; sv, sinus venosa; v, ventricle; vi, ventral interneurons.
