Relationship between the results of sperm analysis and GIFT

Diagnostic significance of sperm-zona pellucida interaction

Spermatozoa binding to the zona pellucida is an early, critical event leading to fertilization and early pre-embryo development. Fertilization involves a complex and orderly sequence of events that is completed at syngamy, which is defined as the union of the two sets of haploid chromosomes to form a new diploid fertilized ovum (zygote). In order to be able to fertilize an oocyte, spermatozoa need to undergo a process called ‘capacitation’, which is usually defined as a series of changes that renders the sperm cells capable of undergoing the acrosome reaction. This process that naturally occurs within the female genital tract is possible under in vitro conditions. However, capacitation is not the only process spermatozoa must undergo to fertilize the oocytes successfully. To fertilize an oocyte, spermatozoa must also be at least highly motile, as well as being capable of undergoing the acrosome reaction timely, penetrating through the oocyte investments and fusing with the oocyte plasma membrane properly.

Clinical value of tests for assessing male infertility

The laboratory assessment of the male partner of an infertile couple is an important aspect of the overall investigation of that couple. The laboratory tests are designed essentially to determine whether (a) the semen samples contain adequate numbers of normal motile sperm, and the sperm are able (b) to migrate to the site of fertilization and (c) to fertilize oocytes. Within this framework, tests can be viewed as being either descriptive, in terms of describing the ejaculate and sperm, or assessing functional qualities of the sperm. Irrespective of the nature of the test, it must satisfy simple criteria, namely being reproducible and able to discriminate between the fertile and infertile populations reliably. External quality assurance programmes now exist for semen analysis and allied techniques to help laboratories to standardize their reporting and to identify the source of possible errors.

Relationship between etiological factors and total motile sperm count in 350 infertile patients

The prevalence of different etiologic factors has been evaluated in 350 male patients consulting the same physician in an urban, ambulatory setting for primary or secondary infertility of more than 1 year. Environmental factors such as alcohol or drugs represented 12% of the etiologies, acquired diseases such as varicocele and prostatitis 40%, congenital diseases and primary testicular failure 16.2%, idiopathic cases 19.4%, and abnormality of sperm transport 7.4%. The severity of sperm alterations in the different etiologic categories was evaluated by the total motile sperm count per ejaculate (TMS) (normal > 16). The TMS was less than 5 in classical causes of male infertility such as testicular failure, endocrinopathy, cancer, or antisperm antibodies. It was more than 10 in controversial causes of infertility such as varicocele, prostatis, chlamydial infections, and professional exposure to heat. After treatment, there was a nonsignificant increase of the TMS in the latter cases. In cases of azoospermia of pituitary origin, the TMS was normalized by a hormonal treatment. In some cases of azoospermia of possible obstructive origin, sperm appeared in the ejaculate after diclofenac treatment. The utility of andrological investigation and treatment is discussed.

In vitro fertilization failure: identification of gamete defects by investigation of sperm-zona pellucida binding capacity of unfertilized oocytes

The objective of the study was to determine whether fertilization failure was due to spermatozoal or oocyte factors. Twenty-five unfertilized oocytes from 12 IVF/GIFT couples showing total or partial fertilization failure were evaluated for sperm zona binding potential under hemizonaeassay (HZA) conditions. Hemizonae were separately incubated with a sperm sample from the husband and that of a fertile control. Tight sperm binding to hemizonae was assessed. First, among the 12 patients, results showed a possible zona defect thought to be the cause of fertilization failure in five cases. Second, in two cases, fertilization failure was possibly caused by poor sperm binding potential of spermatozoa. Third, in two cases, fertilization failure was possibly caused by an oocyte defect, and fourth, three cases showed a mixture of possible causes. The results stress the need to develop a sequential analytic programme for those couples with repeated total or partial fertilization failure.

Strict criteria for the evaluation of human sperm morphology and its impact on assisted reproduction

Sperm morphology abnormalities can be identified in a large proportion of patients with failed and delayed fertilization when assessing this parameter with strict criteria. Statistical analyses of a large IVF population confirm that, in patients with severe teratozoospermia, fertilization rates can be enhanced in many cases by increasing insemination concentration. However, implantation rates are impaired, thereby affecting the ability of these patients to establish a viable pregnancy. Data from couples undergoing controlled ovarian stimulation/intrauterine insemination seem to support the use of strict morphology as a predictor of outcome in this setting, too. Although a descriptive parameter, sperm morphology assessed by strict criteria can be used as a biomarker of sperm dysfunction(s). These dysfunctions are multiple and include abnormalities of motion parameters, poorer capacity to bind to homologous zona pellucidae and penetrate zona-free eggs, and low incidence of spontaneous and induced acrosome reaction. At a cellular level, poor morphology is associated with a higher content of creatine kinase and impaired capacity to undergo appropriate changes in intracellular calcium concentration. Whether nuclear/DNA abnormalities are present still remains to be fully determined. A definitively objective evaluation of morphology based on these criteria may allow all centres specializing in assisted reproduction to analyse semen in a homogeneous fashion.

Prediction of fertilization in vitro with human gametes: is there a litmus test?

OBJECTIVES

The objectives of this study were as follows: (1) to evaluate the relationships between sperm concentration, morphologic pattern, motion parameters, and sperm-zona pellucida binding capacity and (2) to assess their ability to predict fertilization outcome under in vitro fertilization conditions.

STUDY DESIGN

Semen samples from 44 infertile men were prospectively evaluated for density, morphologic pattern (strict criteria), computerized motion parameters (motility, velocity, and linearity), and hemizona assay (outcome expressed as hemizona assay index), and results were correlated with fertilization outcomes of preovulatory oocytes during in vitro fertilization.

RESULTS

Of all sperm parameters, morphologic pattern was the best predictor of the ability of the sperm to bind to the zona pellucida. Hemizona assay index was the best predictor of fertilization rate. Stepwise regression analysis provided a model of hemizona assay index plus motility with highest predictability (R2 = 53.4%).

CONCLUSIONS

(1) The influence of sperm morphologic pattern as a prognosticator of fertilization outcome is established in major part as a determinant of sperm binding ability to the zona pellucida; (2) the hemizona assay provides a robust index that is highly predictive of the potential of human gametes to achieve fertilization and highlights its use in infertility and contraception testing.

Hemizona assay and its impact on the identification and treatment of human sperm dysfunctions

The HZA, a functional test for human gamete interaction, has become a useful and valuable experimental tool for physiological and cellular analysis of the early events leading to fertilization. The analysis of the conventional semen parameters with emphasis on sperm morphology (as judged by strict criteria) and motion characteristics (evaluated by computer assisted analysis) constitutes the first obligatory step for a critical evaluation of male-factor patients. Patients in whom fertilization disorders are suspected should be evaluated through bioassays of sperm function of established accuracy. The HZA, a bioassay of sperm-zona binding capacity is here proven to be highly predictive of IVF outcome. Ultimately, our increasing knowledge of sperm biology and dysfunction will provide a basis for a better diagnosis (membrane receptor defects and metabolic/biochemical abnormalities?) as well as better therapeutic interventions in patients with sperm disorders. It seems likely that the HZA may be eventually replaced by a standardized test kit in which recombinant human DNA-derived zona receptors mimic the natural function of the hemizonae currently used. This ZP3 reagent may also be a useful antigen for contraceptive development. The HZA therefore constitutes a useful adjuvant in the armentarium for the diagnosis and therapy of male-factor patients.

The resazurin reduction test provides an assessment of sperm activity

OBJECTIVE

The objective of the study was to determine if reduction of the dye resazurin by semen could be correlated with the concentration of motile sperm.

DESIGN

After assessment of sperm count and motility, specimens were incubated for 1 hour with resazurin (25 micrograms/mL of semen) and visual color changes indicative of dye reduction noted.

SETTING

Specimens were obtained from men seeking care for infertility at one of four sites: (1) University of California, San Francisco (UCSF) In Vitro Fertilization Program; (2) UCSF Andrology Laboratory; (3) a gynecological practice in Maine; and (4) a private andrology laboratory in Southern California.

PATIENTS

Individuals were self-selected by their desire to have a semen analysis in conjunction with the diagnosis or treatment of infertility.

INTERVENTIONS

None.

MAIN OUTCOME MEASURE

The reduction of the dye resazurin and its correlation with motile sperm density.

RESULTS

When the motile sperm concentration was greater than or equal to 20 X 10(6)/mL, 86% of specimens produced a positive color change. Conversely, 86% of specimens with a motile sperm concentration of less than 20 X 10(6)/mL either did not change color or changed only over a narrow range.

CONCLUSION

Reduction of resazurin offers an assessment of the active sperm in a specimen without the need to do a sperm count or evaluation of motility.