抄録
Hybridization of a nucleic acid probe to nucleic acids within cytological preparations permits a high degree of spatial localization of sequences complementary to that probe. This localization can be useful in a number of ways for answering biological questions. For example, in situ hybridization to the DNA of condensed chromosomes can be used to map the sites of particular sequences. Hybridization to the DNA of interphase nuclei can be used to study the functional organization of specific sequences within the diffuse chromatin that characterizes this stage of the cell cycle. In situ hybridization to cellular RNA allows a very precise analysis of the tissue distribution, as well as the temporal distribution, of any RNA species of interest. In some cases, the distribution of RNA within single cells has interesting biological implications. In addition, in situ hybridization makes it possible to study the RNA of individual cells without interference from the RNA of other cells in the same tissue. Thus it is possible to use the technique to detect RNAs that are present in only a small subset of cells. Such RNAs might never be detected in RNA extracted from a whole tissue because of dilution by other RNA species from the many cells which do not contain the RNA of interest. Because it depends on the concentration of RNA within a cell, rather than within a tissue, in situ hybridization is useful not only to show where an RNA is localized but, in some cases, it may be the best way to show that an RNA exists at all.
