Factors influencing the success rate of human embryo freezing in an in vitro fertilization and embryo transfer program.

Certain factors influencing the success of embryo cryopreservation were analyzed from 124 cycles of in vitro fertilization and embryo transfer (IVF-ET) program in which 193 1- or 2-day embryos were frozen and had already been thawed. There were 100 transfers of one or two surviving embryos from which 26 pregnancies were initiated. Several factors significantly influenced embryo survival after thawing. They were: the developmental stage of frozen embryos; the appearance of the embryo at the time of freezing; and the mode of ovarian stimulation in the IVF cycle. The pregnancy rate after frozen-thawed embryo transfer was higher with 4-cell frozen embryos than with embryos at all other stages combined. There were also tendencies for the pregnancy rate to be higher if a spontaneous luteinizing hormone surge occurred in the transfer cycle or if the duration of embryo storage did not exceed 1 to 2 months. The results obtained support a new policy in IVF-ET programs: it should be advantageous for the sterile couple if the immediate fresh embryo transfer is only performed with the categories of embryos that demonstrate a poor aptitude for survival following cryopreservation procedures.

Influence of different stimulation treatments on oocyte characteristics and in-vitro fertilizing ability.

A retrospective analysis was performed in order to compare the number and quality of oocytes recovered in in-vitro fertilization cycles according to different protocols for ovarian stimulation. Treatments including a gonadotrophin-releasing hormone agonist (GnRHa), either decapeptyl or buserelin, were associated with the recovery of more oocytes (6.0-7.2%) than treatments without GnRHa (3.7-4.8%). However, the mean number of normal embryos per patient yielding oocyte(s) was comparable between cycles stimulated with or without GnRHa (2.4-2.7), except in those cycles programmed with norethisterone and gonadotrophins (1.7). There was no difference in the rates of immature or atretic oocytes between stimulation treatments. Following clomiphene and human menopausal gonadotrophin treatment there was a lower rate of fractured zona oocytes, higher rates of fertilization and normal growth of fertilized eggs than after any other treatment. The proportion of normal embryos per recovered oocyte was inversely related to the degree of ovarian response in most of the stimulation treatments. Most of the abnormal embryos contained more than two pronuclei in cycles without GnRHa administration and exhibited polynucleated blastomeres in cycles treated with buserelin or decapeptyl. In conclusion, the use of GnRHa and gonadotrophins for ovarian stimulation increased the mean number of recovered oocytes, but did not increase the mean number of embryos able to develop.

[In vivo and in vitro fertilizing ability of immature human epididymal spermatozoa]. / Fécondance in vivo et in vitro de spermatozoïdes épididymaires humains immatures.

In cases of congenital absence of vas deferens (9 patients) or after failure of previous epididymovasostomy (2 patients), in vitro fertilization (IVF) was attempted with spermatozoa surgically obtained at the epididymal caput level. These sperm populations showed little progressive motility (5.9 +/- 6.5%) and an marked necrozoospermia (19.3 +/- 17.4%). Stimulation by caffeine (4.5 mM) alone or associated with heterologue normal seminal fluid resulted in most of the cases in an initiation of motility with an improvement of the progressive velocity. In 9 IVF attempts, 31 mature oocytes were inseminated with 5.10(3) to 1.5.10(6) motile spermatozoa. The dynamic characteristics in 3 inseminated sperm populations were Vp (24.2 +/- 8.3 microns/s), Ah (8.6 +/- 2.0 microns) at room temperature. Sperm binding to zona pellucida was decreased (0 to about 20 spermatozoa per oocyte) and there was no fertilization. In the same period, 21 attempts of intra uterine insemination and 14 attempts of intracervical inseminations were made in 5 couples who remained infertile after patent high epididymovasostomy (4) or vasovasostomy (1) and having immature spermatozoa stimulated as previously described. Antisperm antibodies were detected on the ejaculated spermatozoa in four men. No pregnancy was obtained with these immature stimulated spermatozoa. The fertility of the female partners was confirmed in 3 women after insemination with donor sperm.