9-Week Human Embryo from Ectopic Pregnancy

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.

For the photo, I immersed the formalin-fixed specimen in absolute alcohol (which, because of its low specific gravity, allows the specimen to firmly sink to the bottom of the dish and not float around).

I shot the picture with an expensive Nikon D2X, but I used an old, worn, cheap Nikkor f/4 manual-focus 105mm macro lens, courtesy of the eBay shopping experience. In this case, I added a Nikkor 1.4X tele-converter, which gave me just the right image size and working distance. The picture would have been fine without the tele-converter, requiring just a little mote cropping.