Report on a very young dizygotic human twin pregnancy.

Two ova implanted in one uterus were found at the autopsy of a 28-year-old woman. The ovulation age of both implantations has been estimated to be 10-12 days. The presence of two equally large corpora lutea, one in each ovary, indicates that the implanted ova originated from different ovaries. Thus, an "ovulatio biovarialis" seems to be the basis for the dizygotic twinning in this case. The case is believed to be the only documented example of a very early dizygotic, fraternal pregnancy in humans.