Abstract: Fetal cells may be obtained from amniocentesis, chorionic villus sampling, percutaneous umbilical cord sampling or in vitro fertilization embryos or products of conception, but are preferably from maternal peripheral blood. Fetal cells may be enriched by density gradient centrifugation. Fetal cells may also be enriched by removing maternal cells with an antibody to a cell surface antigen, e.g. anti-CD45, either immobilized or by fluorescence-activated cell sorting. Fetal cells are also distinguishable from maternal cells by staining, e.g. with a labeled antibody to cytokeratin or to fetal hemoglobin, or for fetal hemoglobin by hematoxylin/eosin, or by in situ hybridization to detect one or more fetal mRNAs, e.g., of fetal hemoglobin or fetoprotein. Amplification may be used in conjunction with the in situ hybridization. Fetal cells circulating in maternal blood may be separated by flow cytometry, sorting on their intrinsic light scattering properties.

Abstract: Assays for target molecules in biological cells whereby the use of appropriate light absorbing molecules at an appropriate stage of the assay procedure leads to decreased non-specific emission of light and/or decreased autofluorescence.

Abstract: Solutions useful for hybridizing cells and viruses with nucleic acid and antibody probes, their usefulness increased due to the presence of permeation enhancers and signal enhancers, including permeation enhancers; also the hybridization processes wherein the solutions are used.

Abstract: Assays for target molecules in and from cells and viruses, e.g. nucleic acids, wherein non-specific background is decreased by including an analogue of the reporter group, e.g. a non-fluorescent analogue such as fuchsin, of a fluorescent group such as fluorescein, to decrease non-specific backround.