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Apoptose du spermatozoïde et fertilité masculine

Abstract : In order to have a better insight into the implications of apoptosis markers in human ejaculated spermatozoa, the aim of our study was to measure these markers in the spermatozoa collected at different levels in the male genital tract in various physiopathological situations. To analyse the functional quality of these spermatozoa, the analysis of relationships between the expression of these markers and the results obtained after assisted reproductive technology was assessed. The markers analysed are factors that are involved in the initiation and activation of apoptosis (activated poly-caspases, caspases-3, -8, -9) and early (externalisation of phosphatidylsérine, PS), or late (DNA fragmentation) signs of apoptosis. Ultrastuctural analysis of the spermatozoa was also carried out for some samples. Measurement of the expression of activated caspases was subject of adjustment given the heterogeneity of the sperm samples and the low quantity of spermatozoa available. Finally, we decided on measurement using a double staining associating a green fluorescent inhibitor for the activated caspases and a red fluorescen vital staining (Propidium Iodide), with detection either by flow cytometry or by fluorescent microscopy depending on the type of spermatozoa to be analysed. In patients presenting congenital bilateral absence of vas deferens, the proportion of living or dead spermatozoa expressing activated caspases was higher in the testicular spermatozoa than in the epididymal spermatozoa suggesting that the apoptotic process started in the testicles and that epididymal spermatozoa were incapable of initiating apoptosis. Under these conditions, in case of ICSI, the risk of injecting an apoptotic spermatozoa into an ovocyte is higher with the testicular spermatozoa and could explain, in part, the different and inferior results obtained with these testicular spermatozoa, compared with epididymal spermatozoa. In the ejaculated spermatozoa of infertile reciprocal or Robertsonian autosomal translocation carriers, the expression of ultrastructural modifications and biochemical markers of apoptosis (activated caspases, DNA fragmentation, PS externalisation) associated with signs of ultrastructural immaturity was higher than in spermatozoa of fertile men. These results could explain that in the ejaculate of these patients, there is a predominance of chromosomal balanced spermatozoa. The gametes presenting an imbalance would have been preferentially eliminated by apoptosis. In conclusion, the apoptosis markers expressed by ejaculated spermatozoa would reflect the impairment of spermatogenesis with apoptosis initiated and aborted in the testicle associated with maturation and differentiation abnormalities. So measurement of apoptosis markers in spermatozoa could be helpful for the understanding of male infertility, particularly to predict the outcome of assisted reproductive technologies.
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Submitted on : Wednesday, August 29, 2012 - 12:34:58 PM
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  • HAL Id : tel-00726203, version 1

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Florence Brugnon. Apoptose du spermatozoïde et fertilité masculine. Génétique. Université Blaise Pascal - Clermont-Ferrand II; Université d'Auvergne - Clermont-Ferrand I, 2009. Français. ⟨NNT : 2009CLF1MM01⟩. ⟨tel-00726203⟩

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