Parameters and variables used in estimates and computational model.

1 No studies report stiffness of embryonic lung tissue. Range is an estimate. Lower bound: 20 Pa for amphibian embryos; upper bound 400 Pa for ASM cells in vitro.
2 We assume that the viscosity of airway lumen fluid in the embryo is lower than that of neonatal airway mucus but higher than that of blood.
3 Fetal pig airway SM 1–20 kPa, highest in trachea, lowest in bronchioles. We assume this as an upper bound, and that embryonic SM will likely be weaker by 1–2 orders of magnitude. We assume a SM thickness of 15 microns.
4 Fetal pig, pseudoglandular stage
5 Fetal mouse (lowest value).
6 Rabbit fetus, static pressure.
7 Fetal sheep, static pressure.
Parameters and variables used in estimates and computational model.