King B F
Am J Anat. 1987 Jan;178(1):30-44. doi: 10.1002/aja.1001780105.
In this study, closely staged placental villi from rhesus monkeys between 19 and 60 days of gestation were used to examine 1) the origin of endothelial cells and the mechanism of angiogenesis in villi; 2) the origin of placental macrophages (Hofbauer cells), and 3) the origin of the reticular cells that compartmentalize the stroma. The results did not support the concept that early stromal cells in the villi were derived by in situ delamination from cytotrophoblast. The extraembryonic mesodermal (mesenchymal) cells at the earliest of ages examined contained considerable granular ER. These cells organized into groups and formed primitive intercellular junctions, thus giving rise to the early angioblastic masses. The angioblastic masses were cellular, not syncytial; and lumen formation was not the result of intracellular vacuolization, but rather was the result of the acquisition of junctionally defined spaces. The earliest capillaries lacked intravascular blood cells and a basal lamina. Later, blood cells were evident in the lumina. At about 45-50 days of gestation, fetal capillaries began to indent the basal surface of the trophoblast. The basal lamina of the fetal capillaries still had not developed by 60 days of gestation. Between 35 and 40 days of gestation, significant morphological changes took place in the villous stroma. Evidence was obtained that the mesenchymal cells differentiated into the reticular cells that subdivided the stroma into fibril-rich and fibril-free compartments. At the same time, Hofbauer cells were observed for the first time; they occupied the fibril-free regions of the stroma. We did not observe any clear indications of intermediate stages of differentiation between other stromal cell types and Hofbauer cells. It is suggested that placental macrophages may have an origin independent of other stromal types; one possibility is that they are derived from blood monocytes as in other tissues. It is further suggested that the activities of the macrophages and reticular cells may be important in remodeling the extracellular matrix and may be related to the process of branching morphogenesis in the villi.
在本研究中，使用妊娠19至60天的恒河猴紧密分期胎盘绒毛来研究：1）内皮细胞的起源及绒毛血管生成机制；2）胎盘巨噬细胞（霍夫鲍尔细胞）的起源；3）分隔基质的网状细胞的起源。结果不支持绒毛早期基质细胞由细胞滋养层原位分层产生这一概念。在所研究的最早年龄段，胚外中胚层（间充质）细胞含有大量粗面内质网。这些细胞聚集形成团块并形成原始细胞间连接，从而产生早期成血管细胞团。成血管细胞团是细胞性的，而非合体性的；管腔形成不是细胞内空泡化的结果，而是获得连接界定空间的结果。最早的毛细血管缺乏血管内血细胞和基膜。后来，管腔内可见血细胞。妊娠约45 - 50天时，胎儿毛细血管开始压迫滋养层的基底面。至妊娠60天时，胎儿毛细血管的基膜仍未发育。妊娠35至40天时，绒毛基质发生显著形态学变化。有证据表明间充质细胞分化为将基质细分为富含纤维和无纤维区室的网状细胞。同时，首次观察到霍夫鲍尔细胞；它们占据基质的无纤维区域。我们未观察到其他基质细胞类型与霍夫鲍尔细胞之间有任何明确的分化中间阶段迹象。提示胎盘巨噬细胞可能有独立于其他基质类型的起源；一种可能性是它们如在其他组织中一样源自血液单核细胞。进一步提示巨噬细胞和网状细胞的活动可能在细胞外基质重塑中起重要作用，且可能与绒毛分支形态发生过程有关。
