High success rates have been reported for the use of intracytoplasmic sperm injection (ICSI) in alleviating essentially andrological infertility. However, neither the relationship between any of the sperm parameters and the result of ICSI nor the minimal sperm requirements for ICSI have been investigated so far. In this paper, our objective was therefore to study the relationship between three basic sperm parameters (total sperm count, sperm motility and morphology) and the outcome of ICSI by retrospective analyses of fertilization, embryo development and pregnancy rates in 966 micro-injection cycles, performed with ejaculated semen. The results showed that there was no important influence from either the type or the extent of sperm impairment on the outcome of ICSI. Even in the most extreme cases of male-factor infertility, where cryptozoospermia or total astheno- or total teratozoospermia was diagnosed in the initial semen sample, high fertilization and pregnancy rates were obtained by ICSI. Only one condition had a strongly negative influence on the result of ICSI: where an immotile (presumably dead) spermatozoon was injected into the oocyte. Thus the only ultimate criterion for successful ICSI is the presence of at least one living spermatozoon per oocyte in the pellet of the treated semen sample used for micro-injection.

A comprehensive study is presented of a series of 124 infertile men undergoing testicular sperm retrieval for intracytoplasmic sperm injection (ICSI). In this study we correlated the histological changes observed in the testicular tissue with the results of the wet preparation and the outcome after ICSI using testicular spermatozoa. In all patients with normal spermatogenesis and hypospermatogenesis spermatozoa were recovered from the wet preparation. The sperm recovery rate as 84% in patients with incomplete germ-cell-aplasia and maturation arrest, while in patients with complete germ-cell aplasia or maturation arrest this figure was 76%. In these patients more specimens were sampled and fewer spermatozoa were recovered. Since no spermatozoa were recovered in only 10 patients, ICSI with testicular sperm was performed in the remaining 114 couples (91.9%). The normal fertilization rate was 57. 8%. The fertilization rate was significantly lower in couples among whom the husband showed germ-cell aplasia and maturation arrest. Overall, 55.2% of normally fertilized oocytes developed into embryos showing <=50% of anucleate fragments. There were no major differences between the different histological categories in terms of embryonic development in vitro. The overall pregnancy rates per testicular sperm extraction (TESE) procedure, per ICSI procedure and per transfer were respectively 36.3, 39.5 and 43.7%. The overall implantation rate per embryo (sacs/embryos replaced) was 20.3%. A lower implantation rate was observed in couples among whom the husband had maturation arrest (not statistically significant). The above data show that testicular biopsies may have an important therapeutic role in the management of infertility in azoospermic patients.

Knowledge of the timing of the stages of fertilization in humans is still limited because the time of gamete fusion is not known when pre-ovulatory or in-vitro matured cumulus-enclosed oocytes are inseminated. We therefore studied the morphological nuclear changes in 14 patients' oocytes by means of light microscopic observation at 2, 4, 6, 8, 16, 18 and at 20 h after intracytoplasmic single sperm injection (ICSI). A total of 144 metaphase II oocytes were injected with the spermatozoa of the patients' partners. Out of the 134 oocytes that survived the injection, 93 displayed two pronuclei in the course of the observation period (69%). Out of the 93 normally fertilized oocytes, 21 extruded the second polar body at 2 h after micro-injection (23%) and 63 oocytes at 4 h (68%). Pronuclei appeared as early as 6 h after ICSI in 16 normally fertilized oocytes (17%). At 8 h, 75 (80%) oocytes had two visible pronuclei, at 16 h 92 (99%), at 18 h 76 (82%) and at 20 h 63 (68%). In 24 oocytes (26%) the appearance of pronuclei was asynchronous, while the disappearance of the pronuclei was always synchronous, except in one oocyte. Nine of the 134 successfully injected oocytes showed three equal-sized pronuclei (6.7%). Four of the nine multi-pronucleated oocytes did not extrude the second polar body at all, while the time sequence of appearance of pronuclei was similar to that of the normally fertilized oocytes.(ABSTRACT TRUNCATED AT 250 WORDS)

Although the average fertilization rate in most in-vitro fertilization (IVF) centres is approximately 60-70%, there are cases of complete or virtually complete fertilization failures. The aim of our work was to study the fertilization and the subsequent cleavage characteristics of 1-day-old human oocytes treated by intracytoplasmic single sperm injection (ICSI) after failing to fertilize during the standard IVF procedure. A total of 115 metaphase II 1-day-old unfertilized oocytes were collected from 23 patients. No additional treatment was applied to the oocytes or to the semen sample. A single spermatozoon from the patient's husband was injected into the cytoplasm of each of these oocytes 21-33 h after ovum retrieval. Injected oocytes were observed at 16-18 h and again 42-44 h after the ICSI procedure. Of the injected oocytes, 92% (n = 106) were intact after ICSI, 38% (n = 44) had two distinct pronuclei and there was no difference in the fertilization rate of oocytes when andrological and non-andrological patients were compared. Similarly, there was no difference in the fertilization rate after ICSI where patients with acceptable or good (> 15%) fertilization after standard IVF were compared to patients who had poor (< or = 15%) fertilization after IVF. There was no significant difference in the sperm concentration or in the progressive forward motility (a + b motility) in these groups except where a + b motility of andrological and non-andrological patients was compared. The majority (84%) of the normally fertilized oocytes cleaved and most (77%) of these embryos showed < 20% fragmentation 2 days after the ICSI procedure.(ABSTRACT TRUNCATED AT 250 WORDS)

Antisperm antibodies present in the semen can be a primary cause of infertility. If the proportion of spermatozoa carrying antisperm antibodies is very high, then usually a poor result ensues in standard in-vitro fertilization. We therefore employed intracytoplasmic sperm injection (ICSI) in 55 cycles (37 patients) where the proportion of antisperm antibody-bound spermatozoa was 80% or higher, as determined by the mixed antiglobulin reaction (MAR) test. The type and location of antisperm antibodies were determined by the immunobead test in 30 of the 37 patients. The mean normal fertilization rate was 75.7% in these 55 cycles, which was significantly higher than the fertilization rate in another 1767 ICSI cycles (69.2%) performed over the same period and where MAR-negative semen (the level of antisperm antibodies was < 80%) was used for microinjection. Embryonic development was comparable, but a higher proportion of poor-quality embryos was obtained with MAR-positive than with MAR-negative semen samples. Out of the 55 patients, 53 had embryos replaced (96.4%) and a fetal sac was detected by ultrasonography in 14 patients (26.4%). The data indicate that fertilization, embryo development and pregnancy rates after ICSI are not influenced significantly by the proportion of antisperm antibody-bound spermatozoa, nor by the dominant type of antibodies present, nor by the location of the antisperm antibody on the spermatozoa. The conclusion of this study is that ICSI should be the primary choice for patients who have high numbers of antisperm antibodies present in their semen.