The effect of sperm preparation methods on the fertilization rate of oocytes micro-inseminated by subzonal sperm injection

Cumulus oophorus-associated glycodelin-C displaces sperm-bound glycodelin-A and -F and stimulates spermatozoa-zona pellucida binding

Spermatozoa have to swim through the oviduct and the cumulus oophorus before fertilization in vivo. In the oviduct, spermatozoa are exposed to glycodelin-A and -F that inhibit spermatozoa-zona pellucida binding. In this study, we determined whether these glycodelins would inhibit fertilization. The data showed that the spermatozoa without previous exposure to glycodelin-A and -F acquired glycodelin immunoreactivity during their passage through the cumulus oophorus. On the other hand, when glycodelin-A or -F-pretreated spermatozoa were exposed to the cumulus oophorus, the zona pellucida binding inhibitory activity of glycodelin-A and -F was not only removed, but the spermatozoa acquired enhanced zona pellucida binding ability. These actions of the cumulus oophorus were due to the presence of a cumulus isoform of glycodelin, designated as glycodelin-C. The cumulus cells could convert exogenous glycodelin-A and -F to glycodelin-C, which was then released into the surrounding medium. The protein core of glycodelin-C was identical to that in other glycodelin isoforms, as demonstrated by mass spectrum, peptide mapping, and affinity to anti-glycodelin antibody recognizing the protein core of glycodelin. In addition to having a smaller size and a higher isoelectric point, glycodelin-C also had lectin binding properties different from other isoforms. Glycodelin-C stimulated spermatozoazona pellucida binding in a dose-dependent manner, and it effectively displaced sperm-bound glycodelin-A and -F. In conclusion, the cumulus cells transform glycodelin-A and -F to glycodelin-C, which in turn removes the spermatozoazona binding inhibitory glycodelin isoforms and enhances the zona binding capacity of spermatozoa passing through the cumulus oophorus.

Cumulus cells reduce the spermatozoa-zona binding inhibitory activity of human follicular fluid

OBJECTIVE

To investigate the effects of human follicular fluid cultured with cumulus cells to inhibit the binding of spermatozoa to the zona pellucida of oocytes.

DESIGN

Controlled experimental laboratory study.

SETTING

University gynecology unit.

PATIENT(S)

Women undergoing assisted reproduction program and men visiting the subfertility clinics.

INTERVENTION(S)

Culture medium and human follicular fluid were used to culture cumulus cells in vitro for specified time periods.

MAIN OUTCOME MEASURE(S)

Zona binding capacity and motility of spermatozoa after incubation with cumulus cells treated culture medium or human follicular fluid.

RESULT(S)

Compared with the control medium, spent culture media after culturing cumulus cells for 3, 5, and 7 hours did not affect the motility and zona binding capacity of the treated spermatozoa. Significantly more spermatozoa treated with human follicular fluid that had been preincubated with cumulus cells for 5 and 7 hours bound onto hemizona in hemizona binding assay when compared with those preincubated in human follicular fluid without cumulus treatment. The hemizona index increased with the increase in the duration of cumulus cell treatment. Human follicular fluid with or without cumulus cells maintained sperm motility to similar extent for 3 hours.

CONCLUSION(S)

Cumulus cells reduced the inhibitory effect of human follicular fluid on spermatozoa-zona binding in vitro in a time-dependent manner.

Functional motion changes during sperm transit to the site of fertilization and in-vitro applications: a review

Continued research to define the parameters of sperm function should aid the evaluation of various approaches in infertility as well as the efficacy of contraceptives for men which do not necessarily achieve azoospermia. Many treatment forms have been advocated for male factor infertility but have yielded little effect. These included, for example, gonadotrophins, clomiphene citrate, the weakly androgenic steroid, mesterolone. Often, improvements in oligoasthenozoospermia that are not related to genital infection, do not attain normozoospermic levels. Owing to lack of success with various treatment modalities, assisted reproductive technology encompassing artificial insemination by husband or donor following in vitro enhancement of sperm function have assumed an important role in male infertility. Agents that have been shown to induce and support sperm capacitation processes such as hyperactivation, could serve an important role. These include human follicular fluid (HFF), maternal serum, fetal cord serum and methyl xanthine derivatives.

Comparative study of the survival rate of frozen-thawed embryos with perforated zonae from microsurgical fertilization and frozen-thawed embryos with intact zonae

OBJECTIVE

To compare the survival rate of frozen-thawed embryos with perforated zonae from microsurgical fertilization (subzonal insemination) (SUZI) with that of embryos with intact zonae.

DESIGN

Thirty-eight embryos resulting from microsurgical fertilization by SUZI were cryopreserved in 16 patient cycles. Within the same period, 140 zonae-intact embryos from 46 patient cycles were cryopreserved. The survival rate of the SUZI embryos was compared with the zonae-intact embryos after thawing. Clinical pregnancies were compared after the transfer of the thawed embryos.

RESULTS

The total survival rates were 94.7% and 89.3% for thawed SUZI embryos and zonae-intact embryos, respectively. Within each type of embryo, total survival rates were similar irrespective of the age of the embryos at freezing. The blastomere loss per thawed embryo was the same for zonae-intact and SUZI embryos. One clinical pregnancy was obtained in patients who received thawed SUZI embryos and nine in patients who received embryos with intact zonae.

CONCLUSIONS

It is concluded that SUZI embryos can be cryopreserved and thawed with the same degree of confidence as zonae-intact embryos. The low implantation rate of thawed SUZI embryos requires confirmation in a larger clinical series.