Fig. 2. Lrp4 is expressed in multiple tissues and organs during mouse development. (A) Brightfield image of a radioactive in situ hybridization for Lrp4. A cross-section of an E9.5 forelimb bud shows expression of Lrp4 (dark grains) throughout the ectoderm. (B) Dorsal view of an E11.5 hind limb bud shows strong Lrp4 expression (blue) in the AER. (C,D) Whole-mount in situ hybridizations show expression of Lrp4 at the tips of the ureteric buds at E11.5 (C, black arrows) and E16.5 (D). (E) A lateral view of the snout of an E12.5 embryo shows Lrp4 is expressed in whisker primordia. (F) Transverse section through the dorsolateral back region of an E14.5 embryo, counter-stained with Fast Red (pink). Lrp4 is expressed in developing hair follicles (blue). Inset, high magnification view of a hair follicle. (G) Upper palate of an E12.5 embryo. Lrp4 is strongly expressed in the developing incisors and molars. (H) Whole-mount in situ hybridization shows expression of Lrp4 in mammary buds (white arrowheads) at E13.5. (I) Radioactive in situ hybridization (darkfield) for Lrp4 on a sagittal section of a wild-type E12.5 embryo. Lrp4 is expressed strongly in the proximal airways of the lungs (red arrows) and in the diaphragm (white arrow). (J) Transverse section through an E10.5 embryo counter-stained with Fast Red (pink) shows expression of Lrp4 in the dorsal neural tube and floorplate. di, diaphragm; he, heart; in, incisor; lb, limb bud; li, liver; lu, lung; mb, mammary bud; mn, motorneuron; mo, molar; wh, whisker vibrissae.