Skip to main content
. 2020 Dec 17;8:610544. doi: 10.3389/fbioe.2020.610544

FIGURE 2.

FIGURE 2

Stages of placental development. (A) Implantation at 6 to 7 days (d) after conception; (B) prelacunar period (7 to 8 days); (C) beginning of lacunar period (8 to 9 days); (D) transition from lacunar period to primary villus stage (12 to 15 days); (E) secondary villus stage (15 to 21 days); and (F) tertiary villus stage (18 days to week 12). BP, basal plate; BV, blood vessel; CP, primary chorionic plate; CT, cytotrophoblast; D, decidua; E, endometrial epithelium; EB, embryoblast; EG, endometrial gland; EM, extraembryonic mesoderm; EVT, extravillous trophoblast; IVS, intervillous space; M, myometrium; NF, Nitabuch fibrinoid; PB, placental bed; RF, Rohr fibrinoid; SA, spinal artery; ST, syncytiotrophoblast; T, trabeculae; TS, trophoblastic shell; UV, umbilical vein. (Redrawn and modified from Kaufmann, 1981).