Semiautonomous development of the extraembryonic membranes in the chicken embryo.

Based on an old paradigm that the extra-embryonic membranes develop semiautonomously from the embryo, it can also be postulated that subembryonic fluid (SEF) will be formed semiautonomously against embryonic growth, because the formation of SEF is mediated by the yolk sac membrane. In this study, we interfered in the development of SEF or the embryo. The acoustic resonance technique (which measures the resonant frequency of an excited egg) was used as a nondestructive tool to monitor the development of SEF. In the first experiment, in which the embryo was killed chemically with NaN3, it was proven that the formation of SEF continued, even when the embryo was killed after the initiation of the growth of the yolk sac membrane. In the second experiment, in which the development of SEF was inhibited chemically with amiloride, it was shown that the embryo developed further, although SEF formation was inhibited. In the last experiment, it was shown that the age of the flock affected the development of the embryo and the sudden decrease of the resonant frequency in a different way. However, some presetting conditions, such as storage, may affect both in a similar way. Our results further strengthen the idea that the formation of SEF develops semiautonomously against embryonic development by using the nondestructive acoustic resonance technique as an indirect method to monitor yolk sac membrane formation.