Browsing by Author "JEDLICKI, A"

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    EFFECT OF INVIVO OOCYTE AGING ON SPERM CHROMATIN DECONDENSATION IN THE GOLDEN-HAMSTER
    (1986) JEDLICKI, A; BARROS, C; SALGADO, AM; HERRERA, E
    Aged spontaneously activated hamster oocytes recovered from adult females 18 and 24 hours after ovulation were at the pronuclear stage. These oocytes and fresh controls were inseminated in vitro with capacitated hamster spermatozoa and observed with the phase-contrast microscope. The percentage of fertilization in fresh control oocytes was 98%, as compared to 36% and 18% when the oocytes were recovered 18 and 24 hours after ovulation, respectively. The mean number of sperm decondensations per egg in control oocytes was 10, and in the aged ones it was 0.69 and 0.12 when the oocytes were recovered 18 and 24 hours after ovulation, respectively. When similarly treated oocytes were studied with scanning and transmission electron microscopy, it was found that the degree of gamete membrane fusion was greater than that observed with the phase-contrast microscope, but that most of the spermatozoa failed to decondense the chromatin. We suggest that parthenogenetic oocytes at the pronuclear stage are in a similar stage of the cell cycle as in fertilized eggs, in which the cytoplasm does not have the ability to decondense the sperm chromatin.
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    HUMAN SPERM-CERVICAL MUCUS INTERACTION AND THE ABILITY OF SPERMATOZOA TO FUSE WITH ZONA-FREE HAMSTER OOCYTES
    (1988) BARROS, C; JEDLICKI, A; FUENZALIDA, I; HERRERA, E; ARGUELLO, B; VIGIL, P; VILLASECA, P; LEONTIC, E
    Samples of semen and cervical mucus were provided by 18 couples. Cervical mucus was obtained for each day possible and stored at 4.degree.C until all the samples were collected. Flat capillary tubes were loaded with the mucous samples and spermatozoa from the husband''s semen sample were allowed to migrate through the cervical mucus (3 cm column) into culture medium. The spermatozoa recovered after migration through cervical mucus were assayed in vitro with zona-free hamster oocytes. Control experiments were carried out using spermatozoa from the same semen sample but prepared by the swimming-up technique. Altogether, 557 eggs in the control group and 1236 eggs in the experimental group were analysed, and the results demonstrated that the % of sperm penetration, the mean number of sperm decondensations per penetrated egg and the mean number of spermatozoa adhering per egg all had higher values (P < 0.05) for the control samples than for the experimental samples. We suggest that cervical mucus modifies human spermatozoa, as measured by their interaction with zona-free hamster oocytes.
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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.
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    SCANNING ELECTRON-MICROSCOPE STUDY OF INVITRO PREPENETRATION GAMETE INTERACTIONS
    (1985) JEDLICKI, A; BARROS, C
    Hamster and mouse capacitated spermatozoa were interacted in vitro with hamster and mouse eggs in homologous and heterologous combinations. Also, fertilized and trypsin treated unfertilized hamster eggs and unfertilized rat eggs were made to interact with capacitated hamster spermatozoa. The surface of the zona pellucida was then examined with the scanning electron microscope. Sperm attachment, followed by sperm binding and penetration through the zona pellucida, was observed only when homologous gamete combinations were used. Binding of the spermatozoa to the zona was homologous gamete combinations were used. Binding of the spermatozoa to the zona was evidenced by the lytic effect of the acrosomal enzymes on the zona substance. When fertilized eggs and trypsin-treated unfertilized hamster eggs were mixed with capacitated hamster spermatozoa as well as in the heterologous gamete combinations, the spermatozoa were able to establish attachment but not binding. Under these conditions the outer surface of the zona pellucida was never found to have penetration tracks made by the spermatoza. Failure of heterologous spermatozoa to cross the foreign zona pellucida is believed to be associated with the inability of the foreign spermatozoa to establish binding and to the inability of their acrosomal enzymes to digest the zona. A similar mechanism is believed to work in zona-reacted and in trypsin-treated hamster eggs inseminated in vitro with homologous spermatozoa.
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