Museum of Natural History, Leibniz Institute for Research on Evolution and Biodiversity at the Humboldt University Berlin, Invalidenstrasse 43, Berlin, Germany.
Respir Physiol Neurobiol. 2010 Aug 31;173 Suppl:S74-82. doi: 10.1016/j.resp.2010.01.005. Epub 2010 Jan 18.
Appropriate oxygen supply is crucial for organisms. Here we examine the evolution of structures associated with the delivery of oxygen in the pre- and postnatal phases in mammals. There is an enormous structural and functional variability in the placenta that has facilitated the evolution of specialized reproductive strategies, such as precociality. In particular the cell layers separating fetal and maternal blood differ markedly: a non-invasive epitheliochorial placenta, which increases the diffusion distance, represents a derived state in ungulates. Rodents and their relatives have an invasive haemochorial placental type as optimum for the diffusion distance. In contrast, lung development is highly conserved and differences in the lungs of neonates can be explained by different developmental rates. Monotremes and marsupials have altricial stages with lungs at the early saccular phase, whereas newborn eutherians have lungs at the late saccular or alveolar phase. In conclusion, the evolution of exchange structures in the pre- and postnatal periods does not follow similar principles.
适当的氧气供应对生物体至关重要。在这里，我们研究了哺乳动物在产前和产后阶段与氧气输送相关的结构的进化。胎盘具有巨大的结构和功能变异性，这促进了专门生殖策略的进化，如早熟。特别是分隔胎儿和母体血液的细胞层差异显著：非侵入性的上皮绒毛膜胎盘增加了扩散距离，代表了有蹄类动物的衍生状态。啮齿动物及其亲属具有侵入性的血绒毛膜胎盘类型，是扩散距离的最佳选择。相比之下，肺的发育高度保守，新生儿肺部的差异可以用不同的发育速度来解释。单孔目动物和有袋动物具有早产阶段，肺部处于早期囊泡阶段，而新生的真兽类动物的肺部处于晚期囊泡或肺泡阶段。总之，产前和产后交换结构的进化并不遵循类似的原则。
