Pregnancies achieved after frozen-thawed pronuclear oocytes obtained by intracytoplasmic sperm injection with spermatozoa extracted from frozen-thawed testicular tissues from non-obstructive azoospermic men

The use of frozen-thawed testicular tissue as a source of spermatozoa for i ntracytoplasmic sperm injection (ICSI) in non-obstructive azoospermia yield s favourable fertilization and pregnancy rates while avoiding both repetiti ve biopsies and unexpected cycle cancellations. Spermatozoa were obtained f rom frozen-thawed testicular biopsy specimens from 67 non-obstructive azoos permic men. Following fertilization, supernumerary two pronuclear (2PN) ooc ytes were frozen. After thawing, 17 cycles of embryo transfer were carried out with a mean number of 2.7 embryos and a mean cumulative embryo score (C ES) of 18.3 per transfer. The clinical pregnancy and implantation rates per transfer in these cycles (23.5 and 8.3% respectively) were comparable to t hose of fresh embryo transfers (35.7 and 12.7% respectively) with a mean nu mber of 2.7 embryos and a mean CES of 28.7 per transfer. Abortion rates, al though higher with cryopreserved 2PN oocytes were not significantly differe nt. With this approach, cryopreservation of supernumerary 2PN oocytes can b e used to improve the cumulative pregnancy rates in a severely defective sp ermatogenetic population. To our knowledge, these are the first pregnancies reported which have been obtained by the transfer of cryopreserved pronucl ear oocytes obtained from ICSI using cryopreserved testicular spermatozoa.