Krebs C, Winther H, Dantzer V, Leiser R
Institute of Veterinary Anatomy, Histology and Embryology, University of Giessen, Germany.
Microsc Res Tech. 1997;38(1-2):125-36. doi: 10.1002/(SICI)1097-0029(19970701/15)38:1/2<125::AID-JEMT13>3.0.CO;2-R.
The microvasculature of the near-term zonary placenta of the mink has been studied using light microscopy and scanning electron microscopy of corrosion casts, prepared from maternal and fetal vessel systems, respectively. The zonary area, most important for placental exchange, includes a characteristic labyrinth. The labyrinth is composed of lobules oriented in a maternal-fetal direction. One maternal stem artery serves as the central axis of a lobule, and about six pairs of fetal stem arteries and stem veins of the chorionic primary villi mark the periphery of the lobule. Viewed from the fetal side of the labyrinth, this lobular structure presents a roughly hexagonal pattern, with the central maternal stem artery and radially oriented arteriolar branches giving the lobule the shape of a star. These arterioles frequently form bridges to neighboring lobular systems; however, the majority continue into the feto-maternally oriented three-dimensional network of maternal capillary sinusoids, which converge on the outlets of the maternal stem veins on the maternal side of the labyrinth. Maternal main crypts are delimited by the rays of the star-shaped lobules containing chorionic primary villi. The latter penetrate into maternal crypts from the fetal side, and are characterized by their axial arterial and venous stem vessels. Fetal secondary villi are arranged at different levels from these stem vessels. The secondary villi are characterized by arterioles and venules branching in pairs from the stem vessels and supply the tributary capillary complexes of terminal villi. The lobular structure of the placental labyrinth provides a three-dimensional framework of vessels where maternal capillary sinusoids and fetal capillaries meet in a one-way cross-current arrangement. The blood flow conditions and the peculiarities of the mink placenta interhemal membrane are compared to those of other carnivores and discussed with respect to the efficiency of the endotheliochorial placenta.
利用分别由母体和胎儿血管系统制备的铸型腐蚀标本，通过光学显微镜和扫描电子显微镜对水貂足月带状胎盘的微血管系统进行了研究。对胎盘交换最为重要的带状区域包括一个特征性的迷路。迷路由沿母胎方向排列的小叶组成。一条母体主干动脉作为一个小叶的中心轴，约六对胎儿主干动脉和绒毛膜初级绒毛的主干静脉标记着小叶的周边。从迷路的胎儿侧观察，这种小叶结构呈现出大致六边形的图案，中央的母体主干动脉和呈放射状排列的小动脉分支使小叶呈星形。这些小动脉经常形成连接相邻小叶系统的桥；然而，大多数小动脉继续延伸到母胎方向的母体毛细血管血窦的三维网络中，这些血窦汇聚在迷路母体侧的母体主干静脉出口处。母体主隐窝由含有绒毛膜初级绒毛的星形小叶的射线界定。后者从胎儿侧穿透到母体隐窝中，其特征是有轴向的动脉和静脉主干血管。胎儿次级绒毛与这些主干血管处于不同水平排列。次级绒毛的特征是小动脉和小静脉从主干血管成对分支，并为终末绒毛的分支毛细血管复合体供血。胎盘迷路的小叶结构提供了一个血管的三维框架，母体毛细血管血窦和胎儿毛细血管在其中以单向交叉流的方式相遇。将水貂胎盘血膜的血流状况和特点与其他食肉动物的进行了比较，并就内皮绒毛膜胎盘的效率进行了讨论。
