Fig. 2.

Contractile effects of KCl (a), serotonin (5-HT, b), the TP receptor agonist U46619 (c), and endothelin-l (ET-l, d) in extraembryonic arteries (allantoic and yolk sac) from 19-day chicken embryos. Data points are presented as mean ± SE. While the KCl contractions are expressed in mN/mm, the contractions induced by U46619 and ET-I are expressed as percent of the reference KCI-induced contraction in the same vessel. **, ***p < 0.01, 0.001 for difference (yolk sac vs. allantoic) in E _max or at the individual value (in panel d) because E _max was not reached