Long-term follow up amniotic fluid cell cultures brought evidence that in amniotic fluid three types of cells exist, with regard to the rapidity of adherence to the surface of tissue culture flasks. In addition to well known cells, adhering within 1 - 5 days of cultivation, the authors revealed cells rapidly adhering to the surface of transport culture vessels within the range of 1 - 5 hours, during transport of aspirated amniotic fluid to the laboratory and the late adhering cells, which adhere to the culture vessel after 5 - 12 days of cultivation. Rapidly and late adhering amniotic fluid cells are lost by the current method of amniocyte cultivation. Both types of cells provide successful parallel cultures, with 100% cultivation and diagnostic success from the 13th week to the end of gestation. Combination of cultivation of all types of amniotic fluid cells with the cultivation of microfragments of chorionic or placental villi ensures a 100% diagnostic success from the end of Ist to the end of the IIIrd trimester. The time, necessary for obtaining large colonies in vitro and to perform first subcultivation is identical in all types of amniotic fluid cells as well as in chorionic or placental villi cells. In all these cells, a tendency of slower growth after the 30th week of gestation is apparent. The described methods provide a reliable prenatal diagnosis, the greatest possibility to detect chromosomal mosaicism and the chance to finalize results of prenatal diagnosis in the early phase of the second trimeter and to ensure cytogenetic analysis of high risk pregnancies with IUGR or severe congenital anomalies in the IIIrd trimester. This method offers a diagnostic background for new meth ods of biochemical and ultrasound screening in the 9th - 14th week of gestation.

        Key words: prenatal diagnosis, rapidly adhering amniotic fluid cells, slowly adhering amniotic fluid cells, 1st,