Human cells are diploid (contain a double set of chromosomes). The diploid genome is complex and therefore limits genetic research approaches in biomedical models. To overcome this problem experimental generation of haploid stem cells has been done in animals. The investigators aim at generating haploid stem cells from human germ cells that are a useful tool in genetic research and screening.

Human cells are diploid (contain a double set of chromosomes). The diploid genome is complex and therefore limits genetic research approaches in biomedical models. To overcome this problem experimental generation of haploid stem cells has been done in animal models. haploid cells are easier for genetic manipulations, such as knock-in and knock-out of genes, and therefore should make a better experimental model. The investigators aim at generating haploid stem cells from human haploid germ cells.

Inclusion Criteria:

1. males over the age of 18 and under 50
2. no known chronic illness
3. not taking any chronic drugs

Exclusion Criteria:

1. females
2. males under 18 or over 50
3. any known chronic illness
4. taking chronic medications

Male volunteers