Fig. 1.

Decreased oxygen promotes sympathoadrenal lineage differentiation. Sciatic nerve p75⁺P₀⁻ cells were cultured in decreased oxygen or in 20% oxygen, for a total of 12 d, either under standard conditions or with 5 μmforskolin and 1 ng/ml BMP2 added after 6 d of standard culture. Cultures were fixed and stained with antibodies against TH, DBH, and the sympathoadrenal lineage marker SA-1. The barsshow the percentage of stem cell colonies that contained any cells expressing the given markers. Error bars show SEs. Sympathetic markers were expressed at a significantly higher frequency in decreased oxygen and in the presence of forskolin and BMP2 (p < 0.05). In addition, in the presence of BMP2 plus forskolin, there were considerably more TH⁺ cells per colony than in the absence of these factors (see Fig.2A,C).