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F Pellestor

Publications and source records attributed to F Pellestor.

70 records · Page 4Linked to original sources
PubMed1991

Differential distribution of aneuploidy in human gametes according to their sex.

The cytogenetic study of human gametes is a new and important source of information because most chromosomal abnormalities originate from meiotic disorders. The frequency and type of abnormalities were analysed in both spermatozoa and mature oocytes. A total of 13,975 human sperm chromosome complements and 1897 oocyte chromosome complements were analysed. In the present study, pooled cytogenetic data on human gametes have been examined to determine and compare the distribution of non-disjunctions in male and female gametes. Human spermatozoa are characterized by a significant excess of hypohaploidy and an equal distribution of aneuploidies among all chromosome groups, whereas mature oocytes display an equal ratio of hypohaploidy to hyperhaploidy and a high variability in the distribution of non-disjunction: in particular, there is a significant over-representation of aneuploidies in both D and G chromosome groups. This indicates that non-disjunction is not a random event in female meiosis and, consequently, that there are differences in the meiotic process between the sexes. Meiotic and environmental factors which could explain the non-random malsegregation of chromosomes in female meiosis are discussed. The role of maternal age as a cause of aneuploidy is questioned.

Adult↗
PubMed1991

Relationship between sexual abstinence of men and chromosomally abnormal spermatozoa.

Epidemiological and mouse cytogenetic studies have suggested the existence of a positive relationship between the frequency of chromosomal abnormalities and the duration of male sexual abstinence. A cytogenetic analysis of human spermatozoa was performed with 4 men after periods of sexual abstinence ranging from 2 to 15 days. Using hamster eggs for penetration, 934 sperm chromosome complements were obtained. The overall frequency of sperm chromosomal abnormalities was 9.4%. There was no correlation between the length of sexual abstinence and each type of chromosomal abnormality. Our results do not support the hypothesis of an increased risk of aberration with duration of abstinence.

Adult↗
PubMed1991

[Frequency and distribution of aneuploidy in human gametes: differences as a function of sex].

The frequency and the distribution of aneuploidies were analysed in both spermatozoa and mature oocyte. The present study has pooled 13,975 human sperm chromosome complements and 1,897 oocyte chromosome complements examined to date. The overall frequency of aneuploidy is 10% in spermatozoa and 22.4% in oocytes. Human sperm is characterized by a significant excess of hypo-haploidies and an equitable distribution of aneuploidies among all chromosome groups, whereas mature oocytes display an equal ratio of hypo-haploidies: hyper-haploidies and a high variability in the distribution of non-disjunctions; in the A, B, C and especially in D and G groups, there is a significant difference between the observed and estimated rates of non-disjunction and the frequencies expected from an equal partitioning of non-disjunctions among all chromosomes. This indicates that non-disjunction is not a random event in female meiosis, and consequently that there are differences in the meiotic process between the sexes.

Aneuploidy↗
PubMed1990

Analysis of meiotic segregation in a man heterozygous for a 13;15 Robertsonian translocation and a review of the literature.

Meiotic segregation was studied in a male heterozygous for a 13;15 Robertsonian translocation using in vitro sperm penetration of hamster eggs. Sixty-seven sperm chromosome complements were obtained and R-banded. Alternate segregation produced equal numbers of normal (31) and balanced (29) gametes, as was theoretically expected. Incidence of unbalanced complements was 10.4%, and the frequency of abnormalities unrelated to the translocation was 7.4%. This study confirms the predominance of alternate meiotic segregation in Robertsonian translocation carriers. Four sperm studies of Robertsonian translocation have been previously reported. A review of the combined results points out the low incidence of imbalance in the sperm of Robertsonian translocation carrier and the lack of evidence for an interchromosomal effect.

Adult↗
PubMed1990

[Is sexual abstinence a factor in the etiology of chromosome abnormalities?].

Some epidemiological and experimental data in mouse have suggested that there could exist a relationship between sexual abstinence duration and occurrence of chromosomal disorders. In order to determine whether sexual abstinence exerts an effect on the incidence of chromosomal abnormalities in Human, sperm chromosome complements of 4 men were analyzed after fusion with golden hamster eggs. The period of abstinence ranged from 2 days to 15 days. Seven hundred and seventy five karyotypes were obtained. The overall frequency of abnormalities was 9.4% that is not different from controls. There was no correlation between the length of the sexual abstinence and each type of chromosomal abnormality but an indirect effect of paternal aging cannot be excluded.

Adult↗
PubMed1990

[Chromosome abnormalities of human gametes].

Human newborns carrying chromosomal abnormalities are the survivors of a considerably larger cohort of affected conceptions. A direct cytogenetic study of these conceptuses would imply their destruction. Moreover, the ability to determine the parental origin of an additional or missing chromosome is limited from a methodological point of view. The cytogenetic study of human gametes provides information on these mechanisms. Several large-scale studies on sperm complements of normal men give an estimated abnormality rate of 10%. Our results concerning four carriers of reciprocal translocations show no evidence for a selection against abnormal sperm. Since about 30% of the recovered eggs fail to become fertilized in IVF programs, human oocytes have become available for large cytogenetic studies. Analysis of oocytes II provides information on the first meiotic non-disjunction rate. In our sample of 405 karyotypes, the rate of aneuploidy was 27%. No relationship was established between this frequency and the mode of stimulation of ovulation. No increase was observed with maternal aging.

Adult↗
PubMed1989

Direct segregation analysis of reciprocal translocations: a study of 283 sperm karyotypes from four carriers.

Using the technique of in vitro human-hamster fertilization, sperm of four men heterozygous for 4 reciprocal translocations--t(4;17),t(5;13),t(6;7), and t(9;18)--was studied. Frequencies of numerical abnormalities unrelated to the translocations range from 8.3% to 13.3%, and the incidence of imbalances ranges from 23.0% to 66.0%. Results are pooled with data from the nine other reciprocal translocations reported elsewhere, and the combined data demonstrate that male meiotic segregation is not random: whatever the type of translocation may be, the distribution of imbalances in sperm is constant, with approximately 72.0% adjacent 1, 18.5% adjacent 2, and 9.5% 3:1 segregations. The same prevalence of adjacent 1 segregations as that reported at term for translocations of paternal origin is observed. There is a strong postzygotic elimination process; for a given translocation it affects selectively the maximum-imbalance zygotes so that imbalanced segregations observed at term are always predetermined.

Chromosomes, Human↗
PubMed1988

Assessment of aneuploidy in the human female by using cytogenetics of IVF failures.

The karyotype was determined for 201 unfertilized human oocytes recovered from 87 women participating in an in vitro fertilization program. Their mean age was 30.6 years (range 22-40 years). Thirteen oocytes did not exhibit the first polar body and were found to be in the first-metaphase stage. The remaining 188 eggs were assessed as mature and classified into two groups according to the supposed origin of fertilization failure. The overall incidence of aneuploidy was 18.6%. This rate was higher in the group of unexplained fertilization failure (22.5%) than in the group of fertilization failure due to sperm deficiency (10.2%). This may reflect a relationship between the genomic constitution of the oocyte and its fertilizability. On the other hand, no increase of aneuploidy was observed with maternal aging.

Adult↗
PubMed1988

[Spermatozoa karyotyping and meiotic segregation: a study of 4 reciprocal translocations].

Sperm cytogenetics was carried out using technique of in vitro heterospecific human-hamster fertilization. Sperm of 4 men heterozygous from 4 reciprocal translocations (t(4; 17), t(5; 13), t(6; 7) and t(9; 18] was studied. Segregations were various but a majority of unbalanced complements resulting from adjacent 1 segregations was observed. This prevalence was stronger when the pachytene diagram predisposed the translocation to this mode of imbalance at term.

Animals↗
PubMed1987

Chromosome analysis of spermatozoa from a male heterozygous for a 13;14 Robertsonian translocation.

Cytogenetic analysis of 78 spermatozoa from a man heterozygous for a t(13;14) Robertsonian translocation was performed. R banding was applied for chromosomal identification. Incidence of normal and balanced complements were respectively 50% and 41.3%. Six unbalanced complements (7.7%) were observed, resulting from adjacent segregation. Although alternate segregation is the most common mode of distribution, the possibility of producing unbalanced zygotes exists. The frequency of abnormalities unrelated to the translocation was 16.5% including 12.8% hypohaploïdy, 2.5% hyperhaploidy, and 1.2% of structural aberrations. An excess of t(13;14) X complements was observed (24 with X versus 14 with Y). This may result from the close association between trivalent (13;14) and X chromosome observed in the pachytene spermatocyte nucleus.

Adult↗
PubMed1985

[Cytogenetics of human gametes: its application to the study of fertilization anomalies].

A study of 100 sperm karyotypes from 8 normal subjects was carried out using the technique of in vitro hetero-specific human-hamster fertilisation. 19 of those showed some abnormality. 17% of those were hyperploidies or hypoploidies and 2% showed structural abnormalities. A study carried out at the same time on 34 hamster egg karyotypes showed 6 hypoploidies and 1 hyperploidy. In effect oa cytogenetic technique which is very similar to this one makes it possible to analyse the human oocyte karyotype. The results found in these samples of motile sperms show a higher incidence of abnormality than in other published series, but these figures can not be extrapolated to the composition of in vivo whole sperms.

Animals↗
PubMed1985

[Demonstration of human spermatozoa chromosomes in a heterospecific system: technical difficulties].

The incidence of chromosomal abnormalities at conception has been estimated to be very high about 40%; these estimations have been made on indirect evidence provided by karyotyping spontaneous abortions products. Now direct evidence is available, consisting in sperm chromosome analysis by using fertilization of zona-free eggs of the golden hamster. In our experience 175 assays have been performed with modifications of the technique described by Martin et al. (1982) and by Brandriff et al. (1984). Consistent results are obtained since the last 30 assays, using for the first time an R banding technique. Chromosomal analysis of 48 spermatozoa from 7 normal males is reported. The frequency of abnormal sperm complements (21%) is higher than reported by previous reports.

Animals↗
PubMedDate not supplied

Direct estimation of the recombination frequency between the RB1 gene and two closely linked microsatellites using sperm typing.

In this study, single sperm typing has been used for high-resolution recombination analysis between the retinoblastoma gene and two closely linked extragenic microsatellites (D13S284 and D13S1307). The analysis of 1198 single sperm from three donors allowed the determination of recombination fractions between RB1.20 and D13S284 and RB1.20 and D13S1307 of 0.022 and 0.033, respectively. These results show that RB1 gene and the two microsatellites are closely linked, which validates their potential use in indirect genetic diagnosis of retinoblastoma.

Genetic Linkage↗
PubMedDate not supplied

Effect of long abstinence periods on human sperm quality.

OBJECTIVE: To evaluate the effects of long abstinence periods on semen characteristics. DESIGN: Semen analysis was performed on six men after various sexual abstinence periods (from 2 to 18 days). The variations in semen parameters were analyzed statistically as a function of the duration of abstinence. SETTING: The Reproductive Biology Laboratory at the University of Montpellier Medical School. RESULTS: Lengthy sexual abstinence was found to affect all semen characteristics. Semen volume and concentration and total sperm count showed significant increases, whereas motility and normal morphology decreased significantly with duration of abstinence. Significant changes in the percentage of normal sperm forms were observed after more than seven days' abstinence. CONCLUSION: The study indicates that the influence of long sexual abstinence on semen quality varies with the variable considered. With regard to fertility, a long abstinence period might induce senescence of spermatozoa.

Adult↗