cx neo transgene was incorporated into the pgc genome the internal fragments revealed in plasmid dna following digestion with styi ncoi and ecori with kpni were also present in genomic dna from the pgcs indicating that the cx neo transgene was integrated into the pgc genome without alteration using conventional transgene construction techniques additional elements can be incorporated such as regulatory elements tissue specific promoters and exogenous dna encoding proteins are examples monoclonal antibodies are preferred example of a protein encoded by exogenouse dna and human monoclonals are preferred species thereof as noted above the performance of genetic modifications in pgcs to produce transgenic animals has been demonstrated in only a very few species analogous genetic manipulations can be achieved in chicken pgcs by referring to those achieved using es cells in mice in mice the separate use of homologous recombination followed by chromosome transfer to embryonic stem mes cells for the production of chimeric and transgenic offspring is well known powerful techniques of site specific homologous recombination or gene targeting have been developed see thomas k r and m r capecchi cell 51 503 512 1987 review by waldman a s crit rev oncol hematol 12 49 64 1992 insertion of cloned dna jakobovits a curr biol 4 761 763 1994 and manipulation and selection of chromosome fragments.