Fertilization with human testicular spermatids: four successful pregnancies.

Between July 1995 and May 1996, 36 patients with non-obstructive azoospermia of secretory origin underwent intracytoplasmic injection of spermatids. A previous histological biopsy was performed on all patients: 15 had spermatogenic arrest, a further 13 had Sertoli cell-only syndrome, and the remaining eight had post-cryptorchidism tubal atrophy. The ejaculate was duly examined and a complete absence of spermatozoa and spermatids was confirmed, with only bacteria and debris being found. Testicular sperm extraction (TESE) was then performed. In 19 out of 36 cases round spermatids only were found, while elongated spermatids were found in the remaining 17. Both round and elongated spermatids were isolated and used for injection. A total of 135 oocytes at metaphase II were recovered from 19 partners and injected with round spermatids, while 123 mature oocytes from 17 partners were injected with elongated spermatids. The number of oocytes fertilized, as judged by the presence of two pronuclei, was 75 (55.5%) and 71 (57.7%) respectively. By 34 h after injection, the number of embryos which had cleaved to the 2-cell stage was 56 (74.6%) with round spermatids and 55 (77.4%) with elongated spermatids. All cleaved embryos were transferred into the uterus of the partners. Clinical pregnancies were established in two cases of round spermatid cycles (10.5%) (both are still ongoing), and three cases of elongated spermatid cycles (17.6%) (two are still ongoing; one was lost after 8 weeks of gestation). Chromosomal analysis showed that all fetuses had a normal karyotype (three male and one female) with no chromosomal abnormalities.