Culture of naked quail ( Coturnix coturnix japonica) ova in vitro for avian transgenesis: Culture from the single-cell stage to hatching with pH-adjusted chicken thick albumen

Abstract

We first examined the pH change of the albumen of quail ( Coturnix coturnix japonica) eggs before and after they were laid, as well as that of laid eggs. The pH rose rapidly after laying and continued to increase gradually in storage. Incubation at 37.5°C accelerated the increase in the pH of infertile eggs, while that of fertile eggs remained low during incubation. Referring to these results, we obtained a protocol for producing quail hatchlings by culture in vitro from naked ova. The naked ovum was filled with chicken ( Gallus domesticus) thick albumen, the pH of which had been adjusted to 7.2–7.4. The ovum was cultured at 41.5°C in 20% CO 2 in air for the first 24 h. Then the embryo was moved to a surrogate quail egg shell that had been filled with non-pH-adjusted chicken thin albumen and cultured for a further 48 h in 100% air. The embryo was transferred again to a surrogate chicken egg shell and cultured under the same conditions until hatching. The culture yielded quail chicks with a hatchability of 19.4%. The method proposed here should be applicable to the production of transgenic birds.