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Detection of nondisjunction in mammals
Environmental Health Perspectives
|August 1, 1979
Summary
Chromosomal aneuploidy in mammalian germ cells and embryos can be assessed using various methods. X-rays and certain chemicals induce aneuploidy, while hormonal contraceptives at high doses also increase risk.
Area of Science:
- Reproductive toxicology
- Developmental biology
- Genetics
Background:
- Established methods exist for assessing chromosomal aneuploidy in mammalian germ cells and early embryos.
- Combining these methods with chromosome banding enhances data acquisition.
Purpose of the Study:
- To review and synthesize findings on spontaneous and induced chromosomal aneuploidy in mammalian reproduction.
- To evaluate the effects of various agents (x-rays, chemicals, hormones) on meiotic segregation.
Main Methods:
- Review of existing literature on aneuploidy assessment in mammalian oogenesis and spermatogenesis.
- Analysis of studies using x-rays, alkylating agents (trenimone, cyclophosphamide), and hormones (oral contraceptives, ovulation stimulants).
Main Results:
- Spontaneous nondisjunction is rare in mouse and hamster germ cells.
- X-rays significantly increase aneuploidy in oocytes and F1 embryos.
- Alkylating agents induce aneuploidy in oocytes dose-dependently.
- High-dose oral contraceptives increase aneuploidy; ovulation stimulants do not.
Conclusions:
- X-rays and certain chemicals are confirmed inducers of meiotic nondisjunction.
- Further research is needed on species-specificity, stage sensitivity, chronic exposure, thresholds, dose-effect relationships, and the cellular targets of induced nondisjunction.