Delayed Ovulation and Monozygotic Twinning

Bomsel-Helmreich, O.; Papiernik-Berkhauer, E

doi:10.1017/s000156600001388x

Cited by 30 publications

(17 citation statements)

References 4 publications

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“…1995), as in rabbit and pig (Ashworth et al . 1998; Bomsel‐Helmreich & Papiernik‐Berkhauer 1976). McLaren et al .…”

Section: Early Origins Of Individualitymentioning

confidence: 99%

“…However, the impact of twinning may depend on the frequency of natural MZs in experimental animals. Lack of genetic markers constrains studies in genetically inbred species; best estimates are that natural MZ twinning is very rare in mice (McLaren et al 1995), as in rabbit and pig (Ashworth et al 1998;Bomsel-Helmreich & Papiernik-Berkhauer 1976). McLaren et al (1995) reported less than five identical pairs from over 2000 mice born.…”

Section: Non-hormonal Communication: Twin Effectsmentioning

confidence: 99%

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The individuality of mice

Lathe

2004

Genes Brain and Behavior

113

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Mutant mice simulating human CNS disorders are used as models for therapeutic drug development. Drug evaluation requires a coherent correlation between behavioral phenotype and drug status. Variations in behavioral responses could mask such correlations, a problem highlighted by the three-site studies of Crabbe et al. (1999) and Wahlsten et al. (2003a). Factors contributing to variation are considered, focusing on differences between individual animals. Genetic differences due to minisatellite variation suggest that each mouse is genetically distinct. Effects during gestation, including maternal stress, influence later life behavior; while endocrine exchanges between fetus and parent, and between male and female fetuses dependent on intrauterine position, also contribute. Pre and perinatal nutrition and maternal attention also play a role. In adults, endocrine cyclicity in females is a recognized source of behavioral diversity. Notably, there is increasing recognition that groups of wild and laboratory mice have complex social structures, illustrated through consideration of Crowcroft (1966). Dominance status can markedly modify behavior in test paradigms addressing anxiety, locomotion and aggressiveness, to an extent comparable to mutation or drug status. Understanding how such effects amplify the behavioral spectrum displayed by otherwise identical animals will improve testing.

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“…1995), as in rabbit and pig (Ashworth et al . 1998; Bomsel‐Helmreich & Papiernik‐Berkhauer 1976). McLaren et al .…”

Section: Early Origins Of Individualitymentioning

confidence: 99%

Section: Non-hormonal Communication: Twin Effectsmentioning

confidence: 99%

The individuality of mice

Lathe

2004

Genes Brain and Behavior

113

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“…Thus, in animal models, delayed implantation of the embryo is associated with polyembryony in armadillos, while delayed ovulation, frequently occurring in the first cycle after withdrawal of oral contraceptives, 14 induces monozygotic twinning in rabbits. 15 In Brazil, the hormone treatment on women to induce ovulation, whether followed by in vitro fertilization or not, is mostly performed in private clinics. Therefore, it is a reasonable supposition that women with a high standard of life attended at private hospitals would include a high proportion of those who have had assisted fertilization, which is associated with multiple births.…”

Section: Introductionmentioning

confidence: 99%

Twinning rate in a sample from a Brazilian hospital with a high standard of reproductive care

Colletto

Beiguelman

2001

Sao Paulo Med. J.

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CONTEXT: Epidemiological studies on twin births have been motivated mostly by the positive correlation between twinning rate and human fertility, prematurity, low birth weight, increased risk of infant death and long term risk for morbidity. OBJECTIVE: This paper intends to estimate the incidence of multiple births in a private hospital in Brazil with a high standard of reproductive care, and to evaluate the effects of maternal age, gestation order and assisted fertilization on twinning rate. DESIGN: Retrospective analysis. SETTING: First-class tertiary private hospital, São Paulo, Brazil. PARTICIPANTS: The multiple birth rate was investigated among 7,997 deliveries from 1995 to 1998, including 7,786 singletons, 193 twins, 17 triplets and one quadruplet. RESULTS: The rates per 1,000 dizygotic and monozygotic pairs and for triplets were estimated as 19.51, 4.50 and 2.13, respectively. The dizygotic and triplet rates were the highest observed in Brazil up to the present day. The twinning rate among primigravidae older than 30 years was very high (45.02 per 1,000) and was due to a disproportionately high frequency of dizygotic pairs. The triplet rate was also very high among the mothers of this age group (5.71 per 1,000). These facts are strong indicators that these women were the ones most frequently submitted to assisted reproductive techniques. The mean maternal age of the studied population was about six years higher than that estimated for mothers in the general population of southeastern Brazil. Primigravidae aged under 30 years as well as multigravidae showed similar twinning rates, which were almost 20 per 1,000. Among the deliveries of multigravidae older than 30 years, an unusually high frequency of monozygotic twins was observed (7.04 per 1,000), probably as a consequence of the residual effect of long-term use of oral contraceptives. CONCLUSIONS: The dizygotic twinning rate increased from 13.51 to 28.98 per 1,000 over the four years studied, with the twinning rate for primigravidae over 30 years old in 1998 being twice that observed in 1995. The mean maternal age was also high during this period, but the extremely high increase in twinning rate observed cannot be attributed solely to this variable. Assisted fertilization seems to be the most probable cause of this unusually high twinning rate.

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“…(16) Finally, as in lower vertebrates, an association between twinning or partial axial duplication and aging or ''overripening'' of oocytes has been observed in mammals. (17)(18)(19) Figure 1. Bisections to produce mouse zygotes that lack animal (A) or vegetal (B) polar regions and corresponding controls (C).…”

Section: Why the Issue Is Still Openmentioning

confidence: 99%

Scrambled or bisected mouse eggs and the basis of patterning in mammals

Gardner

1999

Bioessays

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Delayed Ovulation and Monozygotic Twinning

Cited by 30 publications

References 4 publications

The individuality of mice

The individuality of mice

Twinning rate in a sample from a Brazilian hospital with a high standard of reproductive care

Scrambled or bisected mouse eggs and the basis of patterning in mammals

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