In situ hybridization for Jagged 1 in mouse stromal cell cultures. Radioactive in situ hybridization of primary mouse stromal cell cultures prepared as described in the text. The probe is visualized by grain deposition in the emulsion layer overlying the cells, which have been counterstained with nuclear fast red. (A) Positive control anti-sense actin probe, 1 week exposure. Grain deposition over cells in excess of background indicates RNA is intact. (B) Negative control, sense Jagged 1 probe, 3-week exposure. Grain deposition over cells is not increased over background, indicating no nonspecific hybridization of control probe. (C) Experimental sample, Jagged 1 anti-sense probe, 3-week exposure. Grain deposition over cells indicates Jagged 1 RNA is transcribed by the majority of stromal cells.