Testicular peritubular cells form an ill-characterized cellular compartment of the human testis, which forms a border with Sertoli cells and spermatogonial stem cells (SSCs). A recently developed culture method has identified parts of the secretory repertoire of human testicular peritubular cells (HTPCs), which includes nerve growth factor. Whether peritubular cells produce glial cell line-derived neurotrophic factor (GDNF) and may thus contribute to the stem cell niche is not known.