FIG. 3.

Development of the skeleton in Plk2^−/− embryos. Skeletal preparations from E14.5 to E18.5 embryos were stained with alcian blue and alizarin red. The ossification centers are stained red, and cartilage tissues are blue. Small embryos are enlarged to show details, so the sizes of the embryos on different embryonic days are not proportional. The labeled ossification centers are some of those that are indicative of the stage of skeletal development for the specified embryonic day (26). The insets at the right are ventral views of E18.5 skeletons showing delayed skeletal development in Plk2^−/− embryos. tr, tympanic ring; pb, parietal bone; hb, cartilage primordium of body of hyoid bone; mb, metatarsal bones; meo, middle ear ossicles; pp, proximal phalanges; st, sternebrae; xp, upper region of xiphoid process.