| Mutants were observed as non-staining ribbons on the surface of the villus. |
| These options include amniocentesis, early amniocentesis, chorionic villus sampling, and ultrasound examination. |
| Another prenatal test, called chorionic villus sampling, can diagnose most, but not all, of the same birth defects as amniocentesis. |
| The smooth muscle cells surround the central lacteal and provide for the pumping action required to initiate the flow of lymph out of the villus. |
| Some birth defects can be diagnosed before birth, using one or more prenatal tests including ultrasound, amniocentesis and chorionic villus sampling. |
| Chorionic villus sampling, which consists in sampling trophoblasts from foetal villi which link the child to the maternal placenta, is still experimental. |
