Embryo resorptions R12, R13 and R21. (A) R12 and R13, day 9. In R12, the embryo is no longer visible. In R13, the embryo is still present but it is located in the uterine lumen. (B) R13, day 9. The decidua capsularis is ruptured. The embryo is encased in its amnion but outside the yolk sac membrane and Reichert’s membrane, which are still located in the original embryonic cavity. The yolk sac membrane exhibits blood islands and is folded due to fluid loss. Between Reichert's membrane and yolk sac membrane, there is maternal hemorrhage. (C) The placental barrier is intact. Blood spaces filled with maternal blood are evident as well as embryonic blood vessels containing nucleated erythrocyte. (D) R21, day 12. There was no visible heartbeat and less fluid in the embryonic cavity. Al – Allantois; Am – Amnion; DC – Decidua capsularis; EC – Embryonic cavity; Em – Embryo; GT – Giant trophoblasts; MH - Maternal hemorrhage; nUL – New uterine lumen; PE – Pericardial effusion; Pl – Placenta; RM – Reichert's membrane; UC – Umbilical connection; YS – Yolk sac.