May 1, 2001;
Xenopus frizzled-5: a frizzled family member expressed exclusively in the neural retina of the developing eye.
We have isolated a new Wnt receptor frizzled family member from Xenopus laevis, Xenopus frizzled-5 (Xfz5
), a likely ortholog of human frizzled-5. Based on Northern and whole-mount in situ hybridization data, Xfz5
is first detected at the late neurula
stage in retinal primordia
. Throughout the tailbud
is expressed exclusively in the neural retina
within the optic vesicles. During tadpole
expression becomes restricted to the ciliary marginal zone. This highly restrictive expression pattern makes Xfz5
an excellent marker for neural retinal tissue
[+] show captions
Fig. 2. (A) Northern blot of Xfz5 expression at different stages of development: O, oocyte stage, numbers correspond to stages according to Nieuwkoop and Faber (1956). The molecular sizes marked correspond to the location and size of the 28S and 18S ribosomal RNA bands on the membrane (according to Schibler et al., 1975). (B–H) Whole-mount in situ analysis of Xfz5 expression. Anterior is to the left, dorsal is up unless noted otherwise. (B,C) Stage 20, lateral (B) and anterior (C) view. An arrowhead marks the border of the ventral mesoderm. Xfz5 expression is seen in two bilateral spots within the anterior neural plate corresponding to the presumptive retinal primordia. (D,E) Stage 25, lateral (D) and dorsal (E) view. Xfz5 is localized to the optic vesicle. (F) Stage 27, lateral view. Xfz5 is localized to the optic vesicle. (G) Stage 32, lateral view, (H) close-up of the same embryo. Xfz5 is clearly localized to the retinal area and excluded from the lens. (I–K) Transverse sections through a stage 27 embryo. Xfz5 is localized to neural retina. bv, brain ventricle; lp, lens placode; nr, neural retina; pr, pigmented retina; ovc, optic vesicle cavity. (L) Stage 40 embryo. Xfz5 is localized to the ciliary marginal zone of the laminated retina surrounding the lens. (M,N) Transverse sections through the eye of a stage 40 embryo. Xfz5 is expressed in differentiating retinoblasts within the ciliary marginal zone. cmz, ciliary marginal zone; l, lens; gcl, the ganglion cell layer; inl, the inner nuclear layer; prl, the photoreceptor layer.