Three experiments were conducted to study hatchability as affected by (1) daily turning of eggs in storage as compared with no positional change using eggs stored 14, 21, and 28 days, (2) prewarming eggs at 21–24 °C for 18 hours prior to setting compared with eggs set directly from the egg cooler using eggs enclosed in Cryovac and flushed with nitrogen gas prior to storage for 14, 21, and 28 days, and (3) vacuuming of eggs enclosed in Cryovac flushed with nitrogen gas compared with a Cryovac package inflated with nitrogen prior to storage for 21 and 28 days.A daily positional change of hatching eggs during storage resulted in improved hatchability compared with no positional change. Prewarming Cryovac-packed, nitrogen-flushed, hatching eggs for 18 hours at room temperature resulted in higher hatchability compared with eggs set directly from an egg cooler operated at 10–12 °C. A storage period × prewarming interaction suggests that when eggs are stored for 14 days or less, prewarming is not beneficial, but if the storage period exceeds 14 days then prewarming enhances hatchability. Vacuuming Cryovac-packaged, nitrogen-flushed, hatching eggs prior to storage for 21 and 28 days did not improve hatchability, probably because the oxygen had been effectively removed by the "nitrogen-flush".
Mammalian development does not recapitulate suspected key transformations in the evolution of the mammalian middle ear