Localization of molecules with restricted patterns of expression in morphogenesis: an immunohistochemical approach.

In a search for molecules with restricted patterns of expression during development, monoclonal antibodies were raised against different transitory structures of the chick embryo. Mice were immunized with cell suspensions from lightly homogenized embryonic tissues explanted from morphogenetically active regions. A convenient immunohistochemical assay was used to screen the hybridoma supernatants on a large scale. It relied on the use of poly(ethylene glycol) as embedding medium. Its water miscibility allowed, in a one-step incubation with antibody-containing supernatants, the dewaxing and rehydration of the tissue sections as well as antibody binding. We report here the usefulness of this approach in selecting monoclonals with unique patterns of immunoreactivity. In this study, cephalic neural crest cells in early or late phase of migration, together with their surrounding tissues, were used as immunogens. The monoclonal antibodies obtained have been classified into regional, cell-lineage, cell-cycle or extracellular material-associated markers. The information provided by the direct visualization of the immunoreactivity of the various monoclonal antibodies on tissue sections, as early as the first round of screening, allows rapid determination of the subsequent strategy to be followed for further characterization of the individual markers.