Additional file 1: of Manipulation of spermatogonial stem cells in livestock species SavvulidiFilipp PtacekMartin Savvulidi VargovaKarina StadnikLudek 2019 The choice of which donor population of germline stem cells to expand in culture is critical for the outcome of germ cell transplantation. In this sense, it is important to mention, that the use of PGCs is less practical as these cells are collected from embryo and there are just few PGCs per embryo [186, 187]. On the other hand, the SSCs (together with gonocytes) offer more practical option due to relatively simple procedure of their collection from the testes of neonates, juvenile or adult donors [12]. (DOCX 13 kb)