Rapid triple-labeling method combining in situ hybridization and double immunocytochemistry

A new, rapid method is described for combining in situ hybridization and immunocytochemistry to define cell populations and to map three-dimensional movements of groups of labeled cells within developing chick embryos. The method allows fluorescently labeled cells to be followed in living embryos and subsequently detected as a permanent reaction product for detailed three-dimensional analysis by immunocytochemistry in histological serial sections. Cell identity can be ascertained using a specific riboprobe and in situ hybridization. With this approach, the movements of two groups of cells can be mapped simultaneously (using two different fluorescent trackers and, subsequently, two different chromogens for immunocytochemistry) to analyze relative movements within an embryo, and when combined with in situ hybridization with a specific riboprobe for cell identity, allows fate mapping studies to be conducted using molecular criteria, rather than solely at morphological/positional criteria. The improved method enables the investigator to extract substantially more information from individual embryos, maximizing the results obtained from labor-intensive fate mapping studies.