A new tool to generate transgenic rats using female germline stem cells from post-natal ovaries.

Primordial germ cells (PGCs) are the precursors of reproductive gametes. They were first identified in the posterior region of embryos at the angle between the allantois and the wall of the yolk sac, and were shown to subsequently migrate into the forming gonadal ridges in early mouse and human embryos of both sexes (Eddy et al., 1981; Bendel-Stenzel et al., 1998). PGCs will eventually differentiate into oogonia/oocytes in the female mammals. At birth, ovaries are filled with primordial follicles, which are differentiated from PGCs/oogonia (De Felici, 2010; De Felici and Barrios, 2013).