Carter A M, Mess A
Physiology and Pharmacology, University of Southern Denmark, DK-5000 Odense, Denmark.
Placenta. 2007 Apr;28(4):259-62. doi: 10.1016/j.placenta.2006.04.010. Epub 2006 Jun 15.
We review recent advances in our understanding of placental evolution with particular focus on the interhaemal barrier. It seems likely that the non-invasive, epitheliochorial placentation of living eutherians is a derived state. However, there is disagreement on whether the last common ancestor of eutherian mammals had an endotheliochorial placenta or a haemochorial one. Research has been stimulated by improved understanding of the relations between the orders of mammals provided by molecular phylogenetics. In part, the uncertainties arise from doubt about how to root the mammalian tree. Resolution of this issue will require improved taxon sampling in molecular analyses. At the same time, we need to foster research in comparative placentation on relevant taxa, particularly at the ultrastructural level. Only then can we ensure that information available about the placenta is adequate to capitalise on future advances in molecular phylogenetics. Examples are given of recent findings that could benefit cladistic analysis of placental evolution.
我们回顾了近期在胎盘进化理解方面的进展，特别关注了血胎屏障。现存真兽类动物的非侵入性上皮绒毛膜胎盘似乎是一种衍生状态。然而，关于真兽类哺乳动物的最后一个共同祖先具有内皮绒毛膜胎盘还是血绒毛膜胎盘存在分歧。分子系统发育学对哺乳动物目之间关系的更好理解推动了相关研究。部分不确定性源于对如何确定哺乳动物进化树根部的疑问。解决这个问题需要在分子分析中改进分类群抽样。与此同时，我们需要促进对相关分类群的比较胎盘学研究，特别是在超微结构层面。只有这样，我们才能确保有关胎盘的可用信息足以利用分子系统发育学的未来进展。文中给出了一些近期发现的例子，这些发现可能有助于胎盘进化的分支分析。
