The effect of solubilized homologous zona pellucida on the human acrosome reaction, sperm-zona binding and motion characteristics of capacitated human spermatozoa

Bastiaan, Hadley Saville (2003-12)

Thesis (PhD)--Stellenbosch University, 2003.

Thesis

ENGLISH ABSTRACT: CHAPTER 1 provides literature based background information to emphasize the use of a sequential, multistep diagnostic schedule for couples in an assisted reproductive program as well as the clinical importance of sperm morphology as recorded by strict criteria during the diagnostic approach of the infertile couple. Furthermore, the chapter includes evidence underlining the growing need for the implementation of the physiologically induced acrosome reaction as an important contribution to the assisted reproductive program. The zona pellucida-induced acrosome reaction (ZIAR), sperm-zona interaction as well as computer-assisted semen analyses were investigated. CHAPTER 2 provides detailed experimental protocols of the materials and methods used in the study. CHAPTERS 3-6 each represent a separate study that was prepared as a scientific paper and encompass the experimental research undertaken in the reproductive biology research laboratory at Tygerberg Hospital to address important aspects of human acrosome processes. In the first study, we aimed to evaluate the regulatory role of the Gi-like protein during the AR of normal sperm donors and the role of intact acrosomes during sperm-zona binding. It seems that pertussis toxin-sensitive Gi-like protein in human spermatozoa plays an important regulatory role in the ZIAR and this underlines the importance of intact acrosomes during sperm-zona binding. In the second study, we aimed to evaluate the relationship between the ZIAR and the percentage normal spermatozoa as well as the sperm-ZP binding potential among men referred for a routine semen analysis. ZIAR testing should become part of the second level of male fertility investigations, i.e., sperm functional testing, since 15% of the andrology referrals revealed an impaired AR response to solubilized ZP. In the third study, we aimed to evaluate the possible relationships between the sperm morphology, the acrosome responsiveness to solubulized human ZP and the sperm-zona binding potential among consecutive andrology referrals and randomly selected IVF cases. ZIAR results provide further information regarding dysfunctional sperm and can be used as an additional diagnostic test since the results predicted fertilization failure during IVF treatment. In the fourth study, we aimed to evaluate changes in the sperm motion characteristics and the occurrence of hyperactivated motility after exposure to ZP among andrology referrals. Solubilized human ZP induces hyperactivated motility among sperm populations that have been capacitated under laboratory conditions. Capacitated spermatozoa have an elevated percentage hyperactivated cells that correlate with the percentage normal spermatozoa in the ejaculate. CHAPTER 7, the general discussion, is brief and concise to avoid unnecessary repetition, underlines the validity of a sequential, multistep diagnostic approach and concludes with the recommendation that the ZIAR should form part of the diagnostic tools in the assisted reproductive program.

AFRIKAANSE OPSOMMING: HOOFSTUK 1 bestaan uit ’n omvattende agtergrondstudie wat bestaan uit die ontwikkeling van diagnostiese toetse, die hantering van die egpaar in die reproduktiewe ondersteunings-program asook op die kliniese belang van spermmorfologie. Die toenemende behoefte aan die implementering van die fisiologies-geinduseerde akrosoomreaksie, as ’n belangrike bydrae tot die reproduktiewe ondersteuningsprogram, word ook beklemtoon. Die zona pellucida geinduseerde akrosoomreaksie (ZIAR), sperm-zonabinding asook rekenaar-bemiddelde semenanalises is ondersoek. HOOFSTUK 2 dek gedetailleerde eksperimentele protokolle van die materiale en metodes wat in die studie gebruik is. HOOFSTUKKE 3-6 behandel die eksperimentele navorsing wat in die laboratorium van die reproduktiewe biologie-eenheid te Tygerberg hospitaal uitgevoer is en wat as ses afsonderlike wetenskaplike publikasies aangebied word. Die doel van die eerste studie was om die regulerende rol van Gi-proteiene tydens die AR van normale spermdonors asook die rol van intakte akrosome tydens sperm-zonabinding te evalueer. Dit kom voor asof Gj-protei'ene in spermatozoa ’n belangrike regulerende rol in die ZIAR speel. Dit beklemtoon die belangrikheid van intakte akrosome tydens sperm-zonabinding. Die doel van die tweede studie was om die verhouding tussen die ZIAR en die persentasie normale spermatozoa asook die sperm-zonabindingspotensiaal tussen mans wat vir ’n roetine semenanalise verwys is te evalueer. ZIAR-toetsing moet deel uitmaak van die tweede vlak van manlike fertiliteitsondersoeke, d.w.s. funksionele toetsing, aangesien 15% van die andrologie pasiente ’n verswakte AR respons tot opgeloste ZP openbaar. In die derde studie was die doel om die moontlike verhoudinge tussen sperm-morfologie, die ZIAR en die sperm-zonabindingspotensiaal onder opeenvolgende andrologie-pasiente asook lukraak geselekteerde IVB-pasiente te evalueer. Die ZIAR-resultate bied verdere informasie aangaande disfunksionele spermatozoa en kan gebruik word as ’n addisionele diagnostiese toets aangesien hierdie resultate mislukte bevrugting tydens IVB behandeling voorspel. Die vierde studie het ten doel gehad om veranderinge in spermmotiliteitseienskappe asook hiperaktiwiteit na die blootstelling aan opgeloste zona onder andrologiepasiente te evalueer. Daar is afgelei dat opgeloste menslike zona hiperaktiwiteit induseer in spermpopulasies wat onder gunstige laboratoriumkondisies gekapasiteer is. Die gekapasiteerde spermatozoa het ’n verhoogde persentasie gehiperaktiveerde spermatozoa getoon wat met die persentasie normale spermatozoa in die ejakulaat korreleer. In HOOFSTUK 7 word aangetoon dat dit noodsaaklik is om die diagnostiese skedule by die hantering van die onvrugbare egpaar te gebruik asook dat die ontwikkeling van die funksionele toestand belangrik is vir die bepaling van ZIAR.

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