n. 1. (nidation) the attachment of the early embryo to the lining of the uterus, which occurs at the *blastocyst stage of development, six to eight days after ovulation. The site of implantation determines the position of the placenta. 2. the placing of a substance (e.g. a drug) or an object (e.g. an artificial pacemaker) within a tissue. 3. the surgical replacement of damaged tissue with healthy tissue (see transplantation).... implantation
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