Fig. 7. Differentiation of noggin cells into neural precursors. (A) Phase contrast micrograph of control cells after transfer to neural progenitor medium; (B) phase contrast appearance of noggin-treated cells after transfer to neural progenitor medium; (C) phase contrast appearance of noggin-treated cells following transfer to neural progenitor medium and attachment to culture surface; (D) same field as C stained with antibody to nestin. (E) Graph showing proportion of control and noggin-treated cells forming nestin-positive colonies after 5 days of growth on a feeder cell layer in the absence or presence of 200 ng/ml noggin followed by 1 week of growth in neural progenitor medium. Bars, A-D, 50 µM.