Fig. 10

The retinotectal map is disorganized in Meis1-depleted embryos. (A-L) Lipophilic fluorescent dyes DiI (red) and DiO (green) were injected into specific axial positions of the retina of fixed 5-dpf wild-type and meis1 morphant embryos and innervation patterns of the ganglion cell axons on the tectum were imaged by confocal microscopy. Nuclei are stained with Hoechst 33258 (blue). The wild-type (A-C) medial-lateral segregation of dorsal (red) and ventral (green) ganglion cell axons in the tectum is lost in meis1 morphants (white arrowheads in (D-F)). Similarly, the wild-type (G-I) anterior-posterior segregation of nasal (red) and temporal (green) ganglion cell axons in the tectum is disorganized in meis1 morphants (white arrowheads in (J-L)). The insets in (C, F, I, L) are lateral views of injected retinas from the embryos shown in the corresponding panels. Retinas are oriented with dorsal up and nasal to the left, while all tectal views are dorsal with anterior to the left. Legend for axial position in the tectum: L, lateral; M, medial; A, anterior; P, posterior. All scale bars = 75 μm. (M) Table describing the frequency of various retinotectal mapping phenotypes observed in meis1 morphants (meis1MO). No retinotectal mapping defects were observed in any wild-type embryos examined.