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Biomedical subjects

M Bergere

Publications and source records attributed to M Bergere.

7 recordsLinked to original sources
PubMed1997

Cryopreserved immature mouse oocytes: a chromosomal and spindle study.

PURPOSE: Cryopreservation of human oocytes might provide an alternative approach to freezing supernumerary embryos obtained during IVF. This process, performed on immature denuded prophase 1 mouse oocytes, was investigated. METHODS: We first investigated the capacity of frozen, immature, murine oocytes to continue in vitro maturation after thawing. We then evaluated the risk to offspring from chromosomal damage by cytogenetical and cytological (spindle) analysis. Finally, we attempted to determine the reasons for and the stage of maturation failure. RESULTS: A total of 700 immature oocytes was frozen, 629 (90%) were recovered intact after thawing, and 53% extruded the first polar body, versus 74% for the control group. Freezing was not accompanied by an increase in aneuploidy in maturing oocytes (18 and 15% for thawed and control oocytes, respectively). Consequently, the first meiotic division occurred normally, without an increase in nondisjunction. Spindle analysis demonstrated only a few abnormalities (15 and 2% for thawed and control oocytes, respectively) incompatible with further development. Oocytes arrested during in vitro maturation were mainly at the metaphase I stage (64 and 76% for thawed and control oocytes, respectively). Whereas 17% of thawed oocytes were blocked before the formation of the first meiotic spindle, this never occurred in the control group. CONCLUSIONS: Immature murine oocytes can withstand cryo-preservation, which is encouraging for future human application of this technique.

Animals↗
PubMed1995

Chromosome 18 analysis by fluorescence in situ hybridization (FISH) in human blastomeres of abnormal embryos after in vitro fertilization (IVF) attempt.

We performed fluorescence in situ hybridization (FISH) with a chromosome 18-specific probe on human abnormal cleaved embryos, fertilized either by two spermatozoa and exhibiting three pronuclei (3 PN) or normally fertilized and exhibiting two pronuclei (2 PN) with subsequent severe fragmentation and/or blocking. The aim of the study was to evaluate the incidence of chromosome 18 anomalies among these embryos in order to evaluate the FISH efficiency on such material and to obtain more precise and complete data than those obtained with classical cytogenetic analysis. For the 3 PN cleaved embryos, FISH confirmed the frequent regulation towards diploidy (25 per cent) and the high frequency of mosaics (53 per cent). For the 2 PN blocked or damaged embryos, FISH permitted chromosome evaluation, which was otherwise impossible with classical cytogenetic techniques: we also found a high mosaic frequency (45 per cent) with these embryos. If this frequency were the same for normally developing embryos, it would be a major obstacle to the reliability of either chromosomal or genetic preimplantation diagnosis.

Blastomeres↗
PubMed1993

[Assisted embryo hatching].

In spite of the progress in in vitro fertilization (IVF), implantation rate of IVF embryos remains low. Many factors seem to be involved in these results. Among them, impairment of the hatching process was incriminated by some authors. Assisted hatching seems to be an interesting method for repeated failures of IVF.

Adult↗
PubMed1991

Chromosome analysis of multipronuclear human oocytes after in vitro fertilization.

Multipronuclear human eggs are frequent after in vitro fertilization. Their chromosome analysis can provide useful information. Before cleavage it can confirm the suspected polyploidy. Among the cleaved multipronuclear eggs it provides an estimation of the incidence of the possible return to diploidy. Ninety-four multipronuclear eggs were fixed at the first, second, or third cleavage according to the air-drying method of Tarkowski with or without colchicine exposure: 60 were successfully analysed. Twelve were stopped before cleavage (six without colchicine treatment and six with colchicine treatment). They were polyploid, confirming the cytological observation. Forty-eight eggs cleaved and were stopped by colchicine treatment and karyotyped. Seventeen eggs (35 per cent) had produced diploid embryos. Mosaicism was frequent (15 cases, 31 per cent). Triploidy was not frequent (8 eggs, 17 per cent). Haploidy constituted the remaining cases (8 eggs, 17 per cent). Our data indicate that the initial count of pronuclei is a reliable test. Multipronuclear one-cell oocytes were confirmed to be polyploid. Furthermore, the developmental capacity of the multipronuclear oocytes is variable. Most of them cleaved. However, many multipronuclear oocytes led to diploid cleaving eggs.

Adult↗
PubMedDate not supplied

Influence of male sexual rest and oocyte aging on parthenogenesis frequency in mice: cytogenetic analysis after in vitro fertilization.

This study was conducted to evaluate the influence of male sexual rest and oocyte aging on fertilization rate and parthenogenesis frequency after in vitro fertilization of mouse oocytes. We used a comparison between cleavage rates and fertilization rates according to chromosomal analysis of oocytes to estimate the parthenogenesis frequency. Fertilization rate was not impaired by male sexual rest. Parthenogenesis frequency was increased by male sexual rest. This effect was enhanced by a concomitant moderate oocyte aging. It is concluded that cleavage rate could not be considered as a reliable test of fertilization after attempted in vitro fertilization in such conditions.

Age Factors↗