Paraffin sections of a uterine wall including the decidua in the 22^nd week of gestation, stained with anti-IDO1 antibody.

<p>The trophoblast-invaded implantation site shows strong staining of vascular endothelial cells (A). In the second quarter of the uterine wall most of the myometrial blood vessels are also labeled (B). The third quarter shows only one vessel stained (C) and in the outermost quarter of the uterus (D) none of the vessels stain for IDO1. Scale bar represents 200 µm.