Because pregnancy is counted from the first day of the mother's last menstrual period, not from conception, the embryos in question are two weeks younger than Dr. Uthman's stated pregnancy duration, as he explains.
This photo of an opened oviduct with an ectopic pregnancy features a spectacularly well preserved 10-millimeter embryo. ....
Even an embryo this tiny shows very distinct anatomic features, including tail, limb buds, heart (which actually protrudes from the chest), eye cups, cornea/lens, brain, and prominent segmentation into somites. The gestational sac is surrounded by a myriad of chorionic villi resembling elongate party balloons. This embryo is about five weeks old (or seven weeks in the biologically misleading but eminently practical dating system used in obstetrics).
Now, fast-forward just two weeks:
The size and anatomic features suggest development equivalent to a nine-week pregnancy (or seven weeks post ovulation). In obstetrics, pregnancy is dated from the first day of the last menstrual period, which is about two weeks prior to the ovulation that resulted in the pregnancy.
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