Fzd expression in the developing hippocampus. (A, B) Negative control in situ hybridizations at P7 (A) and P14 (B). (C-H) Three of six Fzds tested are expressed in the hippocampus during development of synapses. All three Fzds, Fzd3 (C, D), Fzd5 (E, F), and Fzd8 (G, H) are expressed in all three subregions at both P7 and P14. Expression was determined using 20× magnification to differentiate signal from background labeling.