Browsing by Author "AGUIRRE, E"

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    RELATIONSHIP BETWEEN THE LENGTH OF SPERM PREINCUBATION AND ZONA PENETRATION IN THE GOLDEN-HAMSTER - A SCANNING ELECTRON-MICROSCOPY STUDY
    (1984) BARROS, C; JEDLICKI, A; BIZE, I; AGUIRRE, E
    Hamster spermatozoa are able to fertilize a high percentage of zona-intact hamster oocytes when they are preincubated for 2 h in a chemically defined medium. From this time on, the longer the preincubation time the lower the percentage penetration. Spermatozoa preincubated for > 6 h are unable to cross the zona pellucida, retaining their ability to fuse with zona-free hamster oocytes. Zona-intact hamster oocytes were observed with the scaning electron microscope. When the oocytes were inseminated with spermatozoa preincubated for 1-5 h the outer surface of the zona showed the penetrating spermatozoa and the sperm tracks made by those that failed to cross it. With longer preincubation times no penetrating spermatozoa were observed, and very few sperm tacks were present on the outer surface of the zona. Control experiments showed that neither eggs, spermatozoa, nor fertilization were affected by the medium recovered after long preincubations. Care should be taken regarding the preincubation time when using the in=vitro fertilization technique.