1 Division of Medicine, University College London , London WC1E 6JF , UK.
2 Internal Medicine, Gynecology and Reproductive Sciences, Yale School of Medicine , New Haven, CT 06520 , USA.
Biol Lett. 2019 Jul 26;15(7):20190374. doi: 10.1098/rsbl.2019.0374. Epub 2019 Jul 10.
Invasive placentation with extended pregnancy is a shared derived characteristic unique to eutherian mammals that possess a highly effective system of haemostasis, platelets. These are found in all mammals but no other group of animals. We propose that platelets and megakaryocytes (large polyploid nucleated bone marrow cells that produce platelets) evolved from an ancestral 2 N thrombocyte by polyploidization and that the possession of platelets enabled the evolution of invasive placentation. This could explain why invasive placentation is limited to mammals.
具有扩展妊娠的侵袭性胎盘是真兽亚纲哺乳动物所特有的共同衍生特征,它们具有高度有效的止血系统,即血小板。这些存在于所有哺乳动物中,但其他动物群没有。我们提出血小板和巨核细胞(产生血小板的大型多倍体核骨髓细胞)是由祖先的 2N 血小板通过多倍体化进化而来的,并且血小板的存在使侵袭性胎盘的进化成为可能。这可以解释为什么侵袭性胎盘仅限于哺乳动物。