The characterized genes could be candidate genes for male infertility. Furthermore, cryptorchid men have an increased risk for testicular tumors. We have isolated the Insl3 gene which is only expressed in testicular Leydig cells. Mice deficient for the Insl3 gene show bilateral, abdominal cryptorchidism. Therefore these mice can be used as a model system for the study of cryptorchidism in human and for the evaluation of downstream and upstream target genes in the gene cascade.
Testicular seminomas are the most frequently occuring tumors in young men.
To date it is unknown from which type of germ cells seminomas derive from. Using transgenic mice, in which an oncogene is under the control of germ cell specific promoters, this question can be answered. Furthermore, these mouse models are suitable for the isolation and characterization of genes which are involved in malignant germ cell transformation and seminoma development. Targeted disruption of the Insl3 gene causes bilateral cryptorchidism. Male mice deficient for germ-cell Cyritestin are infertile.