[Submicroscopic structure of amniotic fluid cells]

Submicroscopic examination of amniotic fluid cells in the second trimester of pregnancy revealed that the cells are from the morphological aspect a very heterogeneous population, comprising vital and degenerated cells the ultrastructure of which rules out the possibility of cultivation of cells of foetal as well as of maternal origin. As to degenerated cells, the authors identified circular cells with a granular cytoplasm and nucleus originating from the urogenital or digestive tract of the foetus. Furthermore cells with a process and segmented or fragmented pycnotic nucleus derived from granulocytes and macrophages of maternal origin. Also circular cells of the periderm with short microvilli and advanced regressive changes of the nucleus and cytoplasm are degenerated. Among non-vital elements also anuclear completely keratinized cells of the stratum corneum originating from the skin of the maternal abdomen can be included. As to vital elements, the amniotic fluid contains cells of the amniotic ectoderm which are large, have numerous microvilli, a dense margin and a network of filaments in the cytoplasm. They are the most numerous cells. Other vital elements in amniotic fluid include granulocytes and macrophages with a typical ratio of lyzosomes. Both are considered elements of maternal origin. Maternal origin is assumed also in fibroblasts which along with collagen particles may penetrate into the aspirating needle. From the results ensues that the cells in amniotic fluid are not a homogeneous population of unequivocally foetal origin and that a better technique of collection of samples and cultivation must be developed.