Lomholt J P
J Exp Zool. 1976 Nov;198(2):177-84. doi: 10.1002/jez.1401980207.
The 02-permeability of the avian egg shell and shell membranes is initially low (approximately equal to 0.1-10(-6) ml O2 STP-sec-1cm-2-mmHg-1) during incubation but increases about 10-fold after the first week. This increase correlates with a decline in water content of the membranes. A major increase in colloid osmotic pressure (up to 50 cm Hg) occurs and is the suggested cause for the onset of rapid removal of water from the membranes. A high membrane water content correlates with low O2-permeability and vice versa. The final degree of membrane hydration reached during incubation is independent of ambient humidity; that is, the O2-permeability of the shell and its membranes is controlled by conditions inside the egg. An hypothesis is presented to explain the profound increase in O2-permeability while the rate of water loss from the egg remains stable during incubation. The removal of water from the shell membranes by the increased colloid osmotic pressure will increase the number of gas filled channels in the membranes which in turn will increase the O2-permeability. In spite of the change in water content, the water vapor pressure in the shell membranes will always be very close to that of a free water surface and water loss will hence be determined by the ambient humidity and the porosity of the mineral shell.
禽蛋壳及壳膜的氧气渗透率在孵化初期较低（约等于0.1 - 10（-6）毫升氧气标准温度和压力下每秒每平方厘米每毫米汞柱），但在第一周后会增加约10倍。这种增加与膜中水分含量的下降相关。胶体渗透压大幅增加（高达50厘米汞柱），这被认为是膜中水分快速去除开始的原因。膜的高含水量与低氧气渗透率相关，反之亦然。孵化期间达到的膜水合最终程度与环境湿度无关；也就是说，蛋壳及其膜的氧气渗透率由蛋内条件控制。本文提出一个假说，以解释在孵化期间蛋的失水量保持稳定的情况下氧气渗透率大幅增加的现象。胶体渗透压增加导致壳膜中的水分去除，这将增加膜中充满气体的通道数量，进而增加氧气渗透率。尽管水分含量发生变化，但壳膜中的水蒸气压力将始终非常接近自由水表面的水蒸气压力，因此水分流失将由环境湿度和矿物壳的孔隙率决定。
