IN-VIVO GENE-TRANSFER INTO THE BLASTODERM OF EARLY DEVELOPMENTAL STAGE OF CHICKEN

An attempt was made to improve gene transfer into chick embryos in ord er to produce transgenic chickens. The beta-actin-lacZ/MiwZ, a marker gene in transfection reagent, was injected into the blastodisc of eith er unincubated fertilized eggs (stage X) or eggs induced from the shel l gland by treating the hens intravenously with oxytocin or arginine v asotocin (stages IV-VI). All the manipulated embryos were incubated to reach stage XIV, the period at which primordial germ cells (PGCs) mig rate from the germinal crescent to the gonadal anlage via the blood st ream. MiwZ was detected in the embryos, extraembryonic tissues and blo od by the histochemical staining method of beta-galactosidase. The Miw Z DNA was detected in 57% (127/221) of the survival embryos and in 9% (12/127) of the embryonic tissues. The expression was observed mosaica lly in the epidermis, heart and neural tube. The PGCs in the blood col lected from the vitelline artery or dorsal aorta also showed a positiv e histochemical staining. However, the expression of MiwZ using the so ft shelled eggs was more intense in the extraembryonic tissues, althou gh it did not emerge in the embryos. Thus, it is possible to introduce an exogenous gene into the embryonic tissues using incubated fertiliz ed eggs without sacrificing the hens. This technique for successive ge netic operations should facilitate the production of transgenic chicke ns.