(C) Intense anti-Sam68 immunoreactivity was seen in chondrocytes in the nasal septum (panels A–D), in developing vertebra (panels E–H), and in the femoral epiphysis (panels I–K), as well as in diaphyseal osteoblasts (panel L). Adjacent sections were stained with hematoxylin and eosin (panels A, E, and I) or with antibody preadsorbed with the immunizing peptide (panels B, F, and J). Sam68 was localized primarily in the nucleus of cells in a variety of tissues but was also found occasionally in the cytoplasm. Magnification at source ×20, except for panels D, H, and L, which were ×40. Staining patterns are representative of three to five embryos.