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Updated: Jun 10, 2026
02:58
Measurement of Compressive Stress-Strain Response at Small-Strains
Published on: December 5, 2025
The micromass test: Is it subject to strain variation?
1Genetic and Reproductive Toxicology, Glaxo Group Research, Ware, Hertfordshire SG12 0DP, UK.
Summary
Strain differences in rat embryos affect teratogenic responses to all-trans-retinoic acid. In vitro and in vivo studies showed similar susceptibility rankings, suggesting target tissue sensitivity influences teratogenicity.
Area of Science:
- Developmental toxicology
- Pharmacology
- Genetics
Background:
- Strain variation is critical in interpreting regulatory toxicology studies.
- Understanding in vitro-in vivo correlations for teratogenic responses is essential.
Purpose of the Study:
- To compare the teratogenic response of three rat strains (AHA, RH, AP) to all-trans-retinoic acid in vivo and in vitro.
- To investigate the influence of strain differences on limb development and embryonic cell differentiation.
Main Methods:
- In vivo forelimb development assessment and in vitro limb bud and midbrain cell differentiation assays were performed.
- Dose-response curves and ED(50)/IC(50) values were calculated to rank strain susceptibility.
Main Results:
- In vivo, susceptibility order was AHA > RH = AP (ED(50) 93, 124, 123 mg/kg).
- In vitro, limb bud cell differentiation showed marked strain differences: AHA > RH > AP (IC(50) 0.008, 0.09, 0.25 μg/ml).
- Cytotoxicity and midbrain cell differentiation showed minimal strain variation.
Conclusions:
- In vitro micromass tests for retinoic acid are subject to strain variation but predict teratogenic potential accurately.
- Strain susceptibility order was consistent between in vivo and in vitro, indicating target tissue sensitivity is a key factor.
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