This study examined the effects of prenatal visual stimulation on bobwhite quail embryos' growth and heart rate. No differences in growth rate were found between embryos exposed to visual stimulation during the late prenatal period and control embryos. Embryos exposed to visual stimulation throughout incubation maintained lower heart rates in response to visual stimulation than did naïve embryos. In a subsequent experiment, naïve embryos that underwent an egg-opening procedure exhibited heart rates that were lower than embryos measured in intact eggshells. Embryos in opened eggs maintained lower heart rates than comparison embryos across time; however, a less invasive egg-opening procedure led to a quicker heart rate recovery than did a more invasive egg-opening procedure. These findings indicate that prenatal heart rate responses may be mediated by multiple features of the organism's developmental context, including intensity and duration of sensory stimulation.
(c) 2006 Wiley Periodicals, Inc.