Enhanced Binding of Zona Pellucida Proteins: DISCUSSION(9)

Although there was no evidence to suggest that increased zona binding in itself resulted in enhanced instability, the concomitance of the zona binding changes and of cell death in response to IVF conditions was in accord with the general concept of capacitation as a destabilizing process.

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Enhanced Binding of Zona Pellucida Proteins: DISCUSSION(8)

Our flow cytometry analysis of the changes in sZP binding ability of individual cells within the live sperm population has revealed considerable heterogeneity between cells in their speed of response to IVF conditions. One subgroup of sperm underwent the changes relatively rapidly, within the first 60 min of incubation, whereas the rest of the population…

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Enhanced Binding of Zona Pellucida Proteins: DISCUSSION(7)

The mechanism of bicarbonate’s action in increasing zona binding capability remains to be elucidated. The relatively slow time course of the binding change suggests that it results from a multistep process. Given the accelerating effects of caffeine or IBMX in the presence of bicarbonate, it could be that bicarbonate acts through direct stimulation of adenylyl…

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Enhanced Binding of Zona Pellucida Proteins: DISCUSSION(6)

The mature spermatozoon is not considered to have any significant capacity for de novo expression of internally localized membrane components. Thus the increased capacity for binding sZP and the extension of the surface area over which binding occurred would seem to be due to exposure, activation, or increased affinity of already existing structures in the…

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Enhanced Binding of Zona Pellucida Proteins: DISCUSSION(5)

The nature of the sperm surface receptors that mediate the binding of sZP is unknown. Topfer-Petersen and Cal-vete have proposed that the class of small proteins known as “spermadhesins” may play an important role in zona binding of boar sperm; these proteins, which interact strongly with zona components, are produced by the male reproductive tract…

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Enhanced Binding of Zona Pellucida Proteins: DISCUSSION(4)

We believe that the increase in sZP binding ability that takes place within the live spermatozoa is physiologically significant. We envisage that such increases in zona binding ability relate to optimal attachment of the sperm to the zona pellucida, thus improving chances for fertilization. The increased zona binding ability may also reflect sensitization of the…

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Enhanced Binding of Zona Pellucida Proteins: DISCUSSION(3)

Thus our flow cytometric approach, which uses minimally low concentrations of zona material, which obviates the need for pretreatment or washing of the cells (thereby minimizing cell damage), and which enables analysis of some 10 000 cells in less than 15 sec, would seem to provide a sensitive and quantitative evaluation of binding of zona…

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