Imaging for cryptorchidism is not recommended prior to referral, which should occur by 6 months of age. Orchidopexy (orchiopexy is the preferred term) is the most successful therapy to relocate the testis into the scrotum, while hormonal therapy is not recommended. Successful scrotal repositioning of the testis may reduce but does not prevent the potential long-term issues of infertility and testis cancer. Appropriate counseling and follow-up of the patient is essential.

In the human testis, beginning at Ϸ2 months of age, gonocytes are replaced by adult dark (Ad) and pale (Ap) spermatogonia that make up the spermatogonial stem cell (SSC) pool. In mice, the SSC pool arises from gonocytes Ϸ6 days after birth. During puberty in both species, complete spermatogenesis is established by cells that differentiate from SSCs. Essentially pure populations of prepubertal human spermatogonia and mouse gonocytes were selected from testis biopsies and validated by confirming the presence of specific marker proteins in cells. Stem cell potential of germ cells was demonstrated by transplantation to mouse testes, following which the cells migrated to the basement membrane of the seminiferous tubule and were maintained similar to SSCs. Differential gene expression profiles generated between germ cells and testis somatic cells demonstrated that expression of genes previously identified as SSC and spermatogonial-specific markers (e.g., zinc-finger and BTB-domain containing 16, ZBTB16) was greatly elevated in both human spermatogonia and mouse gonocytes compared to somatic cells. Several genes were expressed at significantly higher levels in germ cells of both species. Most importantly, genes known to be essential for mouse SSC self-renewal (e.g., Ret proto-oncogene, Ret; GDNF-family receptor ␣1, Gfr␣1; and B-cell CLL/lymphoma 6, member B, Bcl6b) were more highly expressed in both prepubertal human spermatogonia and mouse gonocytes than in somatic cells. The results indicate remarkable conservation of gene expression, notably for self-renewal genes, in these prepubertal germline cells between two species that diverged phylogenetically Ϸ75 million years ago. mouse spermatogonia ͉ spermatogenesis

Each co-morbidity index provides significant, independent predictive information concerning patient mortality beyond that provided by age, Gleason score and clinical stage alone.