Sperm Cells for Artificial Reproduction and Germ Cell Transplantation

Sperm retrieval for in vitro fertilization/intracytoplasmic sperm injection is the only medical procedure that enables a man with testicular azoospermia to father a child. In obstructive azoospermia after failed refertilization, microsurgical epididymal sperm aspiration is the gold standard, with retrieval rates up to 100%. In nonobstructive azoospermia (NOA), testicular spermatozoa (spermatids) can be recovered by testicular sperm extraction (TESE) in approximately half of the men. No parameters are available to definitively predict a successful recovery individually, but genetic factors, reduced testicular volume, and high serum follicle-stimulating hormone levels are associated with an unfavorable outcome. Retrieval surgery is well standardized, chiefly performed with microsurgical assistance and without severe local complications. Microsurgically assisted TESE (M-TESE) and TESE that is not microscopically supported in low-chance NOA patients may result in hypogonadism in the long term. In patients with Klinefelter syndrome, the outcome is worse with increasing age. For children before chemotherapy, M-TESE for stem cell preservation must be performed with minimal damage to the testicles.