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fetus
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Leonardo da Vinci: pen-and-ink studies of human fetus human fetal brain; prenatal development Diagram showing human embryological and fetal development in three stages: at six weeks, the embryo is enclosed within halved amnion, chorion, and uterus; another view at six weeks highlights the formation of the umbilical cord; at three months, the fetus is shown within the halved amnion, chorion, and uterus, with the placenta and umbilical cord labeled.
Close-up illustration of a human fetus inside the womb, showing the developing baby holding the umbilical cord in a warm, reddish environment.
Pregnancy
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Leonardo da Vinci: pen-and-ink studies of human fetus
Leonardo da Vinci: pen-and-ink studies of human fetus Human fetus, pen-and-ink studies by Leonardo da Vinci, c. 1510.

fetus

embryology
Also known as: foetus
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fetus, the unborn young of any vertebrate animal, particularly of a mammal, after it has attained the basic form and structure typical of its kind. A brief treatment of the fetus follows. For more information on the human fetus, see pregnancy. Biologists arbitrarily speak of the earliest stages of development of the fertilized egg as the embryonic period, which ends when the external form of the embryo begins to resemble clearly the newborn of the...

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