1. Biology of the Testis, Research Laboratory for Reproduction, Genetics and Regenerative Medicine, Vrije Universiteit Brussel (VUB), Laarbeeklaan 103, 1090 Brussels, Belgium
2. Centre for Reproductive Medicine, Universitair Ziekenhuis Brussel (UZ Brussel), Laarbeeklaan 101, 1090 Brussels, Belgium
3. Department of Pediatrics, Division of Pediatric Endocrinology, Universitair Ziekenhuis Brussel, Laarbeeklaan 101, 1090 Brussels, Belgium
4. Reproduction and Genetics, Research Laboratory for Reproduction, Genetics and Regenerative Medicine, Vrije Universteit Brussel (VUB), Laarbeeklaan 103, 1090 Brussels, Belgium
5. Pediatric Endocrinology, Universitair Ziekenhuis Gent, Gent, De Pintelaan 185, B-9000 Gent, Belgium