The group of Ans van Pelt studies the process of sperm development. Sperm cells develop from spermatogonial stem cells that are located in the testis. Healthy men produce 20-200 million sperm cells per day from puberty onwards. This requires a perfect molecular regulated balance between maintaining the pool of stem cells by self-renewal and leaving the stem cell pool by differentiation into sperm. Our lab is interested to identify the molecular mechanisms that contribute to this balance, identification of causes of impaired spermatogenesis in infertile men and establishing potential stem cell based fertility restoration strategies.