ABSTRACT
The Human Genome Project promises a much larger range of possible diagnoses emerging from amniocentesis. Amniocentesis and the other technologies of prenatal screening and diagnosis in use provide access to fetal cells and amniotic fluid and enable the visualization of the developing fetus. These technologies allow detection before birth of all recognizable chromosomal variations, many selected developmental malformations, over 150 biochemical disorders, and fetal sex; the list continues to expand, and the techniques are being applied earlier and earlier in pregnancy. A biopsy of tissue is taken from the site, and the cells of that tissue may be subjected to various genetic and chromosomal tests to detect abnormalities. Chorionic villus sampling is a technique for removing tissue from the chorion—the outermost of the embryonic membranes in mammals—which is generated by the embryo and attaches with a multitude of fingerlike villi to the wall of the uterus, eventually forming the placenta.
