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Fig. 7. Model describing the role of EPHs and ephrins in patterning
chemokine-induced cytotrophoblast invasion. (A) A rapid switch in EPH and
ephrin expression generates repulsive signals that orient cytotrophoblast
(CTB) invasion away from the placenta and towards the uterine wall. (B) Within
the uterine stroma, invasive cytotrophoblasts distinguish veins from
arterioles based on their expression of EPHB4 and ephrin B2, respectively. Our
data suggest that cytotrophoblast interactions with EPHB4-expressing cells
inhibit their chemokine-induced migration, one mechanism that could restrict
their remodeling of veins. By contrast, interactions with ephrin B2-expressing
cells permit migration. As a result, cytotrophoblast remodeling of the uterine
vasculature is biased toward the arterial side of the circulation.