The Avian Germline and Strategies for the Production of Transgenic Chickens

Considerable interest exists in the development of transgenic poultry as a means of improving commercial poultry stocks and for applications in the pharmaceutical industry. The development of transgenic poultry requires stable insertion of genes into the germline. Because of the unique aspects of reproduction in birds, new methods of embryo manipulation had to be developed that include the ex ovo culture of embryos and the formation of germline chimeras using blastodermal cells and primordial germ cells. Currently, transgenic poultry can be produced using retroviral vectors and through the microinjection of DNA into the germinal disk of the newly fertilized egg. However, other approaches such as the development of embryonic stem cells, the culture of primordial germ cells, and sperm-mediated transfection are being explored for their potential to produce transgenic poultry.