Kaufmann P, Luckhardt M, Elger W
Anat Embryol (Berl). 1985;171(2):211-21. doi: 10.1007/BF00341416.
Both placental discs of the tupaia placenta consist of three large mesometrial and numerous additional smaller antimesometrial lobules. The larger lobules can be subdivided into a central (maternal arterial inflow), intermediate (maternal capillaries, exchange area), and a peripheral zone (maternal veins). The ultrastructure of the intermediate lobular zone has been studied from day 21 until day 41 of pregnancy. The materno-fetal barrier is endotheliochorial in structure. The voluminous maternal endothelium is highly differentiated. The adjacent basement membrane, separating endothelium and trophoblast, is constantly interrupted by endothelial and trophoblastic extensions, forming intense interdigitations between both tissue layers. The trophoblast is a multinuclear continuous layer, syncytial or plasmodial in nature. Cytotrophoblast is missing in all stages studied so far. Towards term, the trophoblast differentiates into three distinct types, arranged beneath each other in a mosaic-type pattern: trophoblast with rough e.r. and trophoblast with smooth e.r. as dominating organelles, as well as thin trophoblastic lamellae, almost devoid of organelles. The connective tissue is composed of very compact, epithelium-like cells, whereas connective tissue fibres and interstitial space are virtually absent. Macrophages, undifferentiated fibroblasts and highly differentiated fibroblasts can be observed. There are structural transitions between connective tissue and neighbouring fetal capillary endothelium.
树鼩胎盘的两个胎盘盘都由三个大的子宫系膜叶和许多额外的较小的子宫系膜前叶组成。较大的叶可细分为中央区（母体动脉流入区）、中间区（母体毛细血管、交换区）和周边区（母体静脉）。从妊娠第21天到第41天对中间叶区的超微结构进行了研究。母胎屏障结构为内皮绒毛膜型。大量的母体内皮细胞高度分化。分隔内皮细胞和滋养层的相邻基底膜不断被内皮细胞和滋养层的延伸所中断，在两个组织层之间形成强烈的指状交叉。滋养层是一个多核连续层，本质上是合体的或原质团的。在迄今为止研究的所有阶段都没有细胞滋养层。接近足月时，滋养层分化为三种不同类型，以镶嵌型模式相互排列：以内质网粗糙的滋养层和以内质网光滑的滋养层为主的细胞器，以及几乎没有细胞器的薄滋养层薄片。结缔组织由非常紧密的上皮样细胞组成，而结缔组织纤维和间质空间几乎不存在。可以观察到巨噬细胞、未分化的成纤维细胞和高度分化的成纤维细胞。结缔组织与相邻的胎儿毛细血管内皮之间存在结构转变。
