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From Embryology
Carnegie No. 7700 (figs. 18-22). Described by Hertig and Rock (1941). Hysterectomy. Posterior wall of uterus. Cho- rion, 0.948 x 0.835 mm. Chorionic cavity, 0.55 x 0.498 mm. Embryonic disc, 0.204 x 0.165 mm. Presumed age, 12 days.