What can comparative studies of placental structure tell us? A review
What can comparative studies of placental structure tell us? A review
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DOI：
10.1016/j.placenta.2004.01.011
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发表时间：
2004-04-01
期刊：
影响因子：
3.8
通讯作者：
Carter, AM
中科院分区：
文献类型：
--
作者：
Enders, AC;Carter, AM
真兽类动物胎盘结构的多样性，使得从确定的形式中得出结论是有问题的。无论胎盘是上皮质膜、合体膜、内膜还是血膜，总会有血缘距离缩小的区域。然而，间伐可以通过不同的方法实现。作为铁转运促进器的嗜血区的存在通常与绒毛内膜胎盘有关，但也可在绵羊和山羊(合体)以及羊膜和鬣狗(血膜)中发现。虽然在科内发现相似的绒毛尿囊型胎盘，但结构在序贯水平上开始分化，并且在系统发育的超序贯水平上几乎没有相关性。卵黄囊的形成和功能的不同提供了额外的变异。对于血迹的发育或保留，似乎存在相当大的适应性压力。绒毛尿囊型胎盘。这种类型的胎盘有几个可能的缺点，包括胎儿细胞更容易进入母体，如果早期达到血液循环状况，还会产生氧化应激。无论如何，没有比人类和大猩猩更大的动物有这种类型的胎盘。在像熊、海牛和大象这样体型较大的动物中，都会出现内脉络膜疾病。除了有蹄类动物外，最大的妊娠期最长的动物--鲸鱼也会出现这种上皮膜状况。考虑到哺乳动物进化早期以来的时间长度，很可能在任何目前幸存的哺乳动物中都没有什么未经修改的结构特征。然而，对不同类型的哺乳动物胎盘的更完整的研究应该有助于我们理解哺乳动物之间的相互关系以及胎盘的功能。(C)2004年IFPA和爱思唯尔有限公司。保留所有权利。
The diversity of placental structures in Eutherian mammals is such that drawing generalizations from the definitive forms is problematic. There are always areas of reduced interhaemal distance whether the placenta is epitheliochorial, synepitheliochorial, endotheliochorial or haemochorial. However, the thinning may be achieved by different means. The presence of a haemophagous area as an iron transport facilitator is generally associated with endotheliochorial placentae but is also found in sheep and goats (synepithellochorial) and in tenrecs and hyaenas (haemochorial). Although similar chorioallantoic placentae are found within families, structure begins to diverge at the ordinal level and there is little correlation at the supraordinal level of phylogeny. Differences in formation and function of the yolk sac provide additional variation. There would appear to be considerable adaptive pressure for development or retention of the haemochorial. type of chorioallantoic placenta. This type of placenta has several possible drawbacks including more ready passage of fetal cells to the maternal organism and, should the haemochorial condition be achieved early, oxidative stress. At any rate no animal larger than the human and gorilla has this type of placenta. The endothellochorial condition is found in animals as large as the bears, manatee and elephants. In addition to the ungulates, the epitheliochorial condition is present in the largest animals with the longest gestation periods, the whales. Considering the length of time since the early stages of mammalian evolution, it is probable that few unmodified structural features are present in any currently surviving mammal. Nevertheless, more complete studies of divergent types of mammalian placenta should help our understanding of mammalian interrelationships as well as placental function. (C) 2004 IFPA and Elsevier Ltd. All rights reserved.