Fetal-maternal interface: a chronicle of allogeneic coexistence

Abstract

The existence of allogeneic cells within an individual has been demonstrated in multiple fields such as hematopoietic stem cell or solid organ transplantation, non-depleted blood transfusions and the most common form which is bidirectional maternal-fetal cell trafficking, whereby cells from the fetus pass through the placental barrier. In order to graphically illustrate this early natural phenomenon that initiates the journey of a child's cells within the mother's blood and other tissues, we used a new procedure in microscopy imaging generating Large Scale Panoramic Pictures (LSPP). This technique can also be extended to explore a broad diversity of experimental models.

Keywords: fetal-maternal interface; fish; microchimerism; placenta; tolerance.

Figure 1. (A) LSPP were constructed using MosaiX (authorizing 10% of overlapping), Zstacking with focus correction for each quadrant, Stitching frames algorithm and Extended Focus functions from AxioVision v4.8.2 software. (B) Example of a resulting LSPP of the decidua basalis of a human placenta covering an area of 0.78 mm² with a resolution of 30.5 megapixels. Decidua basalis was parallel to the sectioning surface. The fetal-maternal interface is labeled with PNA-X (Spectrum Green, green) and PNA-Y (Spectrum Orange, red) chromosome-specific probes. FISH was used for sex-typing and Dapi for nuclear staining (blue). The dotted line-delimited zone is the maternal decidua. White arrows show direct invasion of fetal structures into maternal tissue. (C) Common natural maternal cell (XX) distribution within tissues of the decidua. (D and E) Dispersed infiltrating fetal-derived cells (XY) neighboring maternal cells. (F) Two adjacent cells of maternal and fetal origin. Scale bars: (A) 50 µm; (C) 20 µm; (D–F) 10 µm.