Fig. 5.

a Response to electric field stimulation of extraembryonic arteries (allantoic and yolk sac) and intraembryonic allantoic arteries from 19-day chicken embryos. Data points are presented as mean ± SE. Groups without a common letter have a significantly different E _max (p < 0.05). b Representative images of glyoxylic acid-induced fluorescence of catecholamines in the allantoic and yolk sac arteries from 19 days chicken embryos. Fluorescent catecholamine-containing nerve fibers were present in the yolk sac artery and the intraembryonic allantoic artery but totally absent in the extraembryonic allantoic artery. Scale bar 100 µm