Interspecific cell markers and cell lineage in birds

A cell marking technique based on the structural differences existing between the interphase nucleus in two closely related species of birds, the chick and the Japanese quail, is described. In all embryonic and adult cell types of the quail, a large mass of heterochromatin is associated with the nucleolus making quail and chick cells easy to identify at the single cell level after application of any DNA-specific staining procedure and also at the electron microscope level. This method has been largely used to construct chimeras in ovo and to study dynamic processes such as cell migrations or cell lineage segregation during ontogeny. Recently monoclonal antibodies specific for either quail or chick antigenic determinants (for example, class II MHC antigens) have been prepared, increasing the interest of the quail-chick chimera system as an experimental model.