GERM-LINE CHIMERAS CAN PRODUCE BOTH STRAINS OF FOWL WITH HIGH-EFFICIENCY AFTER PARTIAL STERILIZATION

The drug busulphan is known to be cytotoxic to migrating primordial ge rm cells (PGCs). A technique is described in which doses of 0, 25, 50 and 250 mug busulphan in 40 mul sesame oil were injected into the yolk of White Leghorn eggs incubated for 0, 24, 48 and 72 h. The percentag e survival values of these embryos showed that the older the embryo at the time of injection, the greater the survival. Increasing the dose of busulphan decreased the survival. The percentage of embryos showing abnormalities increased with higher doses of busulphan. The number of germ cells in histological sections from gonads of 16-day embryos was estimated and in embryos treated with 50 mug and 250 mug busulphan th e number of germ cells was significantly less than in the controls. Eg gs were injected with 50 mug busulphan at 24-30 h, and at 50-55 h the embryos received an intravascular injection of a germinal crescent cel l suspension containing PGCs from Rhode Island Red embryos. Twenty hat chlings from these experiments were raised to sexual maturity. All the se birds were fertile and half of the breeding groups producing offspr ing from the transferred germ cells at a rate of about 35% of the tota l. The technique would improve the efficiency of producing transgenic gametes.