Upper image shows positivity in clusters of cells , mostly within the red pulp ( there are some positive cells within the white pulp, however).
Lower image is a H&E to demonstrate that mature rbcs are negative for this antibody ( the pink cells with no nuclei).
3rd trimester placenta. Strong positivity is seen in the cytoplasm of trophoblasts. Should the foetal endothelial cells ( within the villi) be also positive?
L/S of developing skeletal muscle.
Arrowheads indicate: red for primary myotube; green for secondary myotube.