Division of Gynecologic Oncology, Department of Obstetrics and Gynecology, State University of New York, Downstate Medical Center, 450 Clarkson Avenue, Box #24, Brooklyn, NY 11203, United States.
Department of Obstetrics and Gynecology, Weill Medical College of Cornell University, 1300 York Avenue, New York, NY 10021, United States.
Placenta. 2011 Sep;32(9):633-644. doi: 10.1016/j.placenta.2011.06.015. Epub 2011 Jul 18.
Placentation was studied histologically and immunocytochemically in black mastiff bats obtained at frequent intervals throughout pregnancy. These were bred in a captive colony or collected from a reproductively-synchronized wild population. During late pregnancy, the single fetus was largely sustained by a discoidal, hemochorial placenta located at the cranial end of the right uterine horn. This invariant positioning was determined by a vascular tuft that developed there both during early pregnancy and non-pregnant cycles. This provided a scaffold for early placental morphogenesis. As development proceeded, small arterioles and venules serving the tuft were converted to large uteroplacental vessels. Within the base of the placenta, these became lined by an unusual vascular epithelium composed of intermingled patches of multilayered endothelial cells and cytotrophoblast. Initially, the endothelium became multilayered by hypertrophy, proliferation, and infolding of its basal lamina. These created endothelial bilayers usually insinuated between basal laminae. The development of temporary gaps in the laminae then permitted further enlargement of the vessels and proliferation of the endothelial cells as monolayer sheets or chains. The latter were interconnected, forming a complex, stratified, cellular network associated with a prominent meshwork of basal laminae. Throughout much of pregnancy, these endothelial cells were cuboidal to columnar and possessed an abundance of basal glycoprotein granules presumably containing basal lamina precursors. The cells also expressed vimentin and frequently von Willebrand factor, but not cytokeratins or desmin. Pronounced thickening of the endothelia and amplification of their basal laminae likely evolved to greatly strengthen the walls of the uteroplacental vessels.
我们对在妊娠期间频繁获得的黑熊犬蝠进行了组织学和免疫细胞化学研究，以研究胎盘形成。这些蝙蝠是在圈养的殖民地中繁殖的，或者是从繁殖同步的野生种群中收集的。在妊娠后期，单个胎儿主要由位于右子宫角颅端的盘状、血绒毛膜胎盘提供营养。这种不变的位置是由在妊娠早期和非妊娠周期中在那里发育的血管丛决定的。这为早期胎盘形态发生提供了支架。随着发育的进行，为丛提供服务的小动脉和小静脉被转化为大的子宫胎盘血管。在胎盘的基部，这些血管由一种不寻常的血管上皮组成，由多层内皮细胞和合体滋养层交织的斑块组成。最初，内皮细胞通过其基底膜的肥大、增殖和内折而变成多层。这些通常在基底膜之间插入内皮双层。然后，层之间暂时出现间隙，允许血管进一步扩大和内皮细胞增殖为单层片或链。后者相互连接，形成一个复杂的、分层的、细胞状的网络，与明显的基底膜网密切相关。在妊娠的大部分时间里，这些内皮细胞呈立方体形到柱状，并且具有丰富的基底糖蛋白颗粒，推测这些颗粒含有基底膜前体。这些细胞还表达波形蛋白，并且经常表达血管性血友病因子，但不表达细胞角蛋白或结蛋白。内皮的明显增厚和其基底膜的放大可能是为了大大增强子宫胎盘血管的壁。
