The ongoing progress in primordial germ cell derivation and cultivation is opening new ways in reproductive biotechnology. This study tested whether functional sperm cells can be matured from genetically manipulated primordial germ cells after transplantation in adult testes and used to restore fertility. We show that spermatogenesis can be restored after mCherry-expressing or GFP-expressing primordial germ cells are transplantated into the testes of sterilized G0 roosters and that mCherry-positive or GFP-positive non-chimeric transgenic G1 offspring can be efficiently produced. Compared with the existing approaches to primordial germ cell replacement, this new technique eliminates the germ line chimerism of G0 roosters and is, therefore, faster, more efficient and requires fewer animals. Furthermore, this is the only animal model, where the fate of primordial germ cells in infertile recipients can be studied.

The availability of genetically modified mice has facilitated the study of mammalian T cells. No model has yet been developed to study these cells in chicken, an important livestock species with a high availability of gd T cells. To investigate the role of gd and ab T cell populations in birds, we generated chickens lacking these T cell populations. This was achieved by genomic deletion of the constant region of the T cell receptor g or b chain, leading to a complete loss of either gd or ab T cells. Our results show that a deletion of ab T cells but not gd T cells resulted in a severe phenotype in knockout chickens. The ab T cell knockout chickens exhibited granulomas associated with inflammation of the spleen and the proventriculus. Immunophenotyping of ab T cell knockout chickens revealed a significant increase in monocytes and the absence of CD4+ T cells and FoxP3+ regulatory T cells compared to wild type chickens. In addition, we observed a significant decrease in immunoglobulins, B lymphocytes, and changes in the bursa morphology. Our data reveal the consequences of T cell knockouts in chickens and provide new insights into their function in vertebrates.