Figure 1.

The possible role of collagen and its fragment at the maternal fetal interface. The collagen at the maternal fetal interface is mainly produced by trophoblast and decidual stromal cell (DSC). Collagen might play an important role in the trophoblast adhesion, proliferation and invasion. But the process of trophoblast invasion is accompanied by collagen degradation and remodeling, and then produces a number of collagen fragments. The fragment of collagen might be able to inhibit the trophoblast invasion. In addition, collagen and its fragment seem to have the opposite effect in spiral artery remodeling. Collagen may promote the spiral artery remodeling. However, the fragment of collagen seems to be able to inhibit the proliferation and migration of vascular smooth muscle cell (VSMC) and endothelial cell. In addition, collagen promotes immune tolerance of decidual immune cells (DICs). dNK: decidual natural killer cell; T: T cell; Mφ: macrophage.