Comparative aspects of trophoblast development and placentation.
Comparative aspects of trophoblast development and placentation.
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DOI：
10.1186/1477-7827-2-46
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发表时间：
2004-07-05
期刊：
影响因子：
--
通讯作者：
Enders, Allen C
中科院分区：
文献类型：
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作者：
Carter, Anthony M;Enders, Allen C
根据分离母体和胎儿血液的组织数量，胎盘分为上皮绒毛膜胎盘、内皮绒毛膜胎盘或血绒毛膜胎盘。我们回顾了这些胎盘类型的发生在真兽目哺乳动物的各种订单的框架内的四个总的分子遗传学技术确定。非洲兽亚目在古非洲分布广泛，其现存的代表动物包括大象、海牛、蹄兔、土豚、象鼩和马岛猴。异节动物，包括犰狳、食蚁兽和树懒，在南美洲多样化。这两个最古老的总目的胎盘都是内皮绒膜的或血绒膜的。Euarchontoglires的总目包括两个姐妹群，Glires和Euarchonta。前者包括啮齿动物和兔形目动物，它们通常具有血绒膜胎盘。最原始的Euarchonta成员，树，有endotheliochorial胎座。飞狐猴和所有高等灵长类动物都有血绒膜胎盘。然而，狐猴和懒猴在灵长类动物中具有上皮绒膜胎座形成的特殊性。劳亚兽是最后出现的一个总目，包括几个具有上皮绒膜胎座式的目。这些动物包括鲸鱼、骆驼、猪、反刍动物、马和穿山甲。相反，几乎所有的食肉动物都有内皮绒膜胎盘，而蝙蝠有内皮绒膜或血绒膜胎盘。在劳氏兽中也包括一些食虫动物，它们具有许多保守的形态特征;这些动物都没有上皮绒毛膜胎座。胎盘型的分子遗传学的研究结果表明，非洲兽的进化可能的路径是从endotheliochorial到hemochorial胎盘。这也是Xenarthra和蝙蝠的可能场景。我们认为，一个明确的epitheliochorial胎盘是一个次要的专业化，它进化了两次，一次在Laurasiatheria和一次在狐猴和懒猴。
Based on the number of tissues separating maternal from fetal blood, placentas are classified as epitheliochorial, endotheliochorial or hemochorial. We review the occurrence of these placental types in the various orders of eutherian mammals within the framework of the four superorders identified by the techniques of molecular phylogenetics. The superorder Afrotheria diversified in ancient Africa and its living representatives include elephants, sea cows, hyraxes, aardvark, elephant shrews and tenrecs. Xenarthra, comprising armadillos, anteaters and sloths, diversified in South America. All placentas examined from members of these two oldest superorders are either endotheliochorial or hemochorial. The superorder Euarchontoglires includes two sister groups, Glires and Euarchonta. The former comprises rodents and lagomorphs, which typically have hemochorial placentas. The most primitive members of Euarchonta, the tree shrews, have endotheliochorial placentation. Flying lemurs and all higher primates have hemochorial placentas. However, the lemurs and lorises are exceptional among primates in having epitheliochorial placentation. Laurasiatheria, the last superorder to arise, includes several orders with epitheliochorial placentation. These comprise whales, camels, pigs, ruminants, horses and pangolins. In contrast, nearly all carnivores have endotheliochorial placentation, whilst bats have endotheliochorial or hemochorial placentas. Also included in Laurasiatheria are a number of insectivores that have many conserved morphological characters; none of these has epitheliochorial placentation. Consideration of placental type in relation to the findings of molecular phylogenetics suggests that the likely path of evolution in Afrotheria was from endotheliochorial to hemochorial placentation. This is also a likely scenario for Xenarthra and the bats. We argue that a definitive epitheliochorial placenta is a secondary specialization and that it evolved twice, once in the Laurasiatheria and once in the lemurs and lorises.