Institute of Cell Biology, Histology and Embryology, Medical University Graz, Austria Harrachgasse 21/7, 8010 Graz, Austria.
Hum Reprod. 2010 May;25(5):1127-36. doi: 10.1093/humrep/deq035. Epub 2010 Feb 22.
Routes of trophoblast invasion seem to be clear, whereas specific invasive pathways need further elucidation. Extravillous trophoblasts (EVTs) transform spiral arteries to guarantee appropriate blood flow to the placenta in the second trimester. Embryo nutrition during the first trimester is thought to be histiotrophic, whereas proof that EVTs also invade uterine glands is lacking. We developed novel three-dimensional confrontation co-culture models to elucidate invasion of EVTs into uterine glands.
First trimester decidua parietalis and placental villous explants were directly confronted and co-cultured for 72 h, or confronted indirectly after 72 h pre-culture for re-epithelialization of decidua pieces. Cryosections were stained by immunohistochemistry or immunofluorescent/immunohistochemical double labelling and compared with first trimester placentation sites in situ.
EVTs deeply invaded decidual tissues in direct confrontation assays and were found between the decidual epithelial cells and epithelial basement membrane. EVTs were also detected in the decidual stroma in direct proximity to glands, sometimes even replacing glandular epithelial cells. Similar observations were made in sections from the first trimester decidua/placental bed. In the invaded parts of sections of decidua basalis, 55% +/- 7% (mean +/- SEM; n = 10, range 6-11 weeks) of glandular cross sections were associated with or infiltrated by EVTs.
Using novel confrontation co-culture assays, a potential new route of EVT invasion was detected. EVTs appear to break through the basement membrane of uterine glands to open their lumen towards the intervillous space. These data support the hypothesis of histiotrophic nutrition of the embryo prior to onset of maternal blood flow within the placenta.
滋养细胞浸润的途径似乎很明确，但具体的浸润途径仍需进一步阐明。绒毛外滋养细胞（EVT）可使螺旋动脉转化，以保证妊娠中期胎盘有适当的血流。人们认为胚胎在妊娠早期的营养来自组织滋养，但缺乏 EVT 也侵入子宫腺的证据。我们开发了新的三维对峙共培养模型，以阐明 EVT 侵入子宫腺的过程。
将第一孕期的子宫壁蜕膜和胎盘绒毛外植体直接对峙并共培养 72 小时，或在 72 小时预培养后间接对峙，以重新上皮化蜕膜片。通过免疫组织化学或免疫荧光/免疫组织化学双重染色对冷冻切片进行染色，并与原位第一孕期胎盘位置进行比较。
EVT 在直接对峙实验中深度浸润了蜕膜组织，位于蜕膜上皮细胞和上皮基底膜之间。EVT 也在靠近腺体的蜕膜基质中被发现，有时甚至取代了腺上皮细胞。在第一孕期的蜕膜/胎盘床切片中也观察到了类似的现象。在基底蜕膜切片的浸润部分，55% +/- 7%（平均值 +/- 标准差；n = 10，范围 6-11 周）的腺横切面与 EVT 相关或被 EVT 浸润。
使用新的对峙共培养实验，检测到 EVT 浸润的潜在新途径。EVT 似乎突破了子宫腺的基底膜，打开了通向绒毛间腔的腔道。这些数据支持了胚胎在胎盘内母体血流开始前存在组织滋养营养的假说。
