Figure 3. Expression of the 2 rFIP-2s during rat embryogenesis. (A) Histology of the rat embryo at 17 days. Hematoxylin and eosin staining was performed on the sagittal section from the rat embryo. Bar equals 200 µm. mx, maxilla; md, mandible; tg, tongue. (B) In situ hybridization in rat embryo at 17 days. Using rFIP-2A or B anti-sense riboprobe, we observed strong signals for the rFIP-2A and B mRNA in condensing mesenchymal cells of the palatal process (a,b,c,d) and surrounding Meckel’s cartilage (e,f,g,h), while they are absent in the neighboring chondrogenic cells (a to h). The results are shown as bright- (a,c,e,g) and dark-field (b,d,f,h) views. The hybridization signals of rFIP-2A (a,b,e,f) and rFIP-2B (c,d,g,h) were detected by autoradiography at 1 wk, and similar results were obtained after three-week exposure (data not shown). No significant signal was detected on any sections in the case of sense riboprobe for rFIP-2A or B (data not shown). Bar equals 50 µm.