Fig. 1.

Continuous exposure to 0.1–100 μmforskolin does not stimulate S-phase entry in mammalian utricle cells.A, B, Pieces of utricular sensory epithelium fixed after 72 hr in culture in the standard medium in the continuous presence of 10 μm (A) or 100 μm(B) forskolin (Forsk). Nuclei of cells that entered S-phase and incorporated BrdU were stainedblack after immunocytochemistry and were visualized by differential interference contrast (DIC) microscopy. C, Histogram of the level of BrdU labeling in epithelia showing no significant increase in S-phase entry after a 72 hr treatment with forskolin when compared with control cultures in 1% DMSO.Inset, Timeline. The standard medium consisted of 2.5% FBS and 3 μg/ml BrdU with either 1% DMSO (Control) or forskolin at 0.1–100 μm present from the start of the experiment (S). After 72 hr in culture the tissues were fixed (F) and processed for immunocytochemistry. Scale bars, 100 μm.