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Fig. 3. Expression of Six3 subfamily members during Xenopus head development. (A,F) Frontal views of stage 20 embryos showing Six3.2 (A) and Six6.1 (F) expression in the optic field (op) and future ventral forebrain (arrow). (B–D,G–I) Lateral views of embryonic stages 30 (B,G), 35 (C,H) and 39 (D,I) stained for Six3.2 (B–D) and Six6.2 (G–I). The arrowhead indicates the pineal gland primordium and the arrow highlights the olfactory bulb. (E,J) Transverse head sections of stage 35 embryo at the level of the cement gland illustrating Six3.2 (E) and Six6.2 (J) expression. The developing lens (arrowhead), the ventral floor of the diencephalon (de) and the dorsal portion of Rathke's pouch (arrow) are indicated. (K,L) Transverse sections through the head of stage 39 embryos stained for Six3.2 (K) and Six6.2 (L). The insets illustrate Six gene expression in the eye. Arrowheads indicated head mesenchyme. Abbreviations: cg, cement gland; gcl, ganglion cell layer; inl, inner nuclear layer; lv, lens vesicle; op, optic field; os, optic stalk; p, pharyngeal endoderm; rpe, retinal pigment epithelium; tg, tegmentum. |