“While the natural fertilization occurs after the loss of sperm by the acrosome, l’ICSI (Intra-Cytosplamic Sperm Injection) for the entire sperm.
While the introduction of the acrosome does not prevent humans the occurrence of fertilization, team wondered if it does not diminish the frequency.
This question is based on theoretical and experimental. First of all, the acrosome is a bag located in the anterior part of the sperm head that contains substances needed to cross the zona pellucida. Some of them have properties protease that could be harmful to the oocyte. Moreover, in some species (hamsters syria), ICSI with whole sperm injection leads to failure of fertilization when it is productive after destruction of the acrosome. In fact the tolerance observed in humans (and other animal species) is due to the relatively large size of the egg that would withstand this toxicity acrosomale.
This hypothesis is supported by the relationship between tolerance and oocyte volume for the different species studied (hamster, pork, oxen, man, mouse).
The authors hypothesize that current practices, contrary to the physiology of fertilization, reduce the chances of success, or even completely destroy in special cases (concentration of acrosin or oocyte vulnerability in some couples ICSI failure ?). The parade therapy this disadvantage appears to be relatively simple since it is possible to eliminate the acrosome of spermatozoa selected by putting them in contact with non-anionic detergent or lysolecithin. A rinsing step then would complete the processing of sperm prior to intra-oocyte. It must be very fast because of the probable increased fragility of the sperm without acrosome.
Further studies are planned before moving to the voluntary efforts of couples to evaluate a possible gain in terms of fertility.”
- PNAS on line – 09/2005, found in French http://www.labovialle.com/actualite.htm#2
- The original article in English on pnas.org
- For the record : fertilization by ICSI, explanations Fivfrance
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