Endometriosis

Tests of human sperm function and fertilization in vitro

Sperm-zona pellucida binding and penetration were assessed on the oocytes that failed to fertilize from couples with >/=3 oocytes treated by standard in-vitro fertilization (IVF). There were four groups: fertilization rate 0% (n = 369), 1-25% (n = 194), 26-50% (n = 81) and 51-95% (n = 100). Of the couples with zero fertilization rate 70% had </=5 spermatozoa bound per zona pellucida and 42% had no spermatozoa penetrating the zona pellucida of any oocyte. In contrast, in the 51-95% fertilization rate group, only 17% had </= 5 spermatozoa bound per zona pellucida and 6% had no spermatozoa penetrating the zona pellucida. There was a significantly higher frequency of poor sperm morphology (</= 5% normal) in couples with zero fertilization rate (36%) than in the fertilization rate group 51-95% (7%). Incubation of oocytes from 68 couples with zero fertilization rate and low sperm-zonae pellucidae binding with fertile donor spermatozoa resulted in normal sperm-zona pellucida binding and most zonae pellucidae being penetrated. In conclusion, defective sperm-zona pellucida interaction was the major cause for low fertilization rates in standard IVF. This was usually because of defects of the spermatozoa rather than defects of the oocytes. Sperm defects likely to cause failure of fertilization should be diagnosed before commencing IVF and the patients directed to intracytoplasmic sperm injection.

Defective sperm–zona pellucida interaction: a major cause of failure of fertilization in clinical in-vitro fertilization

The morphology of spermatozoa bound to the zona pellucida (ZP) of 264 oocytes that had failed to fertilize in 58 in vitro fertilization procedures was studied by light microscopy. The percentage of spermatozoa with normal morphology bound to the ZP (mean 77, range 8-100) was significantly higher than in the insemination medium (mean 42, range 2-80). The abnormal spermatozoa bound to the ZP had small oval (47%), pyriform (46%), amorphous (5%) and tapering (2%) heads. Other abnormalities of morphology were not observed in ZP-bound spermatozoa. The mean rates of binding to the ZP of spermatozoa with normal morphology (44, 95% confidence limits 42-46, number bound/ZP/10(5)/ml inseminated) were much higher than for abnormal spermatozoa with small oval 6.5 (5.5-7.6), pyriform 5.9 (4.8-7.3), amorphous 1.0 (0.5-2.0) and tapering 2.5 (1.2-5.3) heads. The morphologically abnormal forms not found on the ZP were infrequent in the insemination medium (tail defects, large oval, round, pin and duplicate heads and cytoplasmic droplets) but upper 95% confidence limits for standardized binding ratios of less than 60% indicated that these were unlikely to bind to the zona with rates approaching those of normal spermatozoa (standardized binding ratio 180%). A large number of uniformly normal spermatozoa bound to the ZP when the percentage normal morphology in the insemination medium was greater than 40%. The proportions of abnormal spermatozoa in the insemination medium. Spermatozoon head dimensions were measured with a micrometer in samples from 14 patients. While there were no consistent changes in all samples, the means for head width and area were significantly larger and the ratio of the length to width was smaller for spermatozoa on the ZP than for those in the insemination medium. The head length and ratio of length to width of spermatozoa in samples with good morphology were significantly less than in samples with poor morphology. The percentage of spermatozoa with normal morphology, motility and the ratio of head length to width in the insemination medium were positively correlated with the percentage of spermatozoa with normal morphology bound to the ZP. Logistic regression analysis showed that the diagnosis of tubal infertility and the rate of binding of spermatozoa with normal morphology to the ZP were positively related to fertilization rates in vitro while the rate of binding of spermatozoa with pyriform heads was negatively related. In conclusion. human ZP are highly selective for spermatozoa with normal morphology. The frequency of binding of abnormal spermatozoa to the ZP was mainly dependent on semen quality.(ABSTRACT TRUNCATED AT 400 WORDS)

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Morphology of spermatozoa bound to the zona pellucida of human oocytes that failed to fertilize in vitro.

1. Anatomical and compartmental analysis Peter Sutovsky and Gaurishankar Manandhar 2. Sperm chromatin stability and susceptibility to damage in relation to its structure Jeffrey A. Shaman and W. Steven Ward 3. Genomic and proteomic approaches to defining sperm production and function Sarah Conner, Linda Lefievre and Christopher L. R. Barratt 4. The epididymis and sperm maturation Trevor Cooper and C. H. Yeung 5. Control of motility Claude Gagnon and Eve de Lamirande 6. Regulation of capacitation Pablo Visconti and B. M. Gadella 7. ROS's: friend or foe John Aitken and Liga Bennetts 8. Testing sperm manufacturing quality: the sperm-zona binding assay Sergio Oehninger and Daniel Franken 9. Genetics: a basic science perspective Peter Vogt 10. Sex chromosome abnormalities and male infertility: a clinical perspective Shai Shefi and Paul J. Turek 11. Epigenetic patterning in male germ cells: importance of DNA methylation to progeny outcome Jacquetta Trasler and Sophie La Salle 12. The DAZ gene family and human germ cell development from embryonic stem cells Mark S. Fox, Renee A. Reijo Pera and Amander T. Clark Index.

The Sperm Cell: Production, Maturation, Fertilization, Regeneration

The number of sperm bound to the zona pellucida (ZP) were counted on 660 oocytes that failed to fertilize in vitro from 162 patients. Oocytes from clutches in which some fertilized had significantly more sperm bound to the ZP than did those from clutches in which all oocytes failed to fertilize. Oocytes from patients in whom all were not fertilized and no sperm bound to the ZP were able to bind normal fertile donor sperm after storage in ammonium sulphate solution. The number of sperm bound to the ZP was significantly related to the proportion of sperm with normal morphology and normal intact acrosomes in semen, sperm concentration inseminated, sperm motility and viability. The number of sperm bound to the ZP, sperm normal morphology, diagnosis of male infertility and sperm concentration in semen were significantly related to the fertilization rate by logistic regression analysis. Thus the number of sperm bound to the ZP is an indicator for IVF success and low binding appears to be more frequently associated with sperm defects than oocyte defects.

W.I.H. Johnston

Papers

Human sperm—zona pellucida binding, sperm characteristics and in-vitro fertilization