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[Histological study of micrognathic development in mouse fetus induced by 3,3-dimethyl-1-phenyltriazene]
1Department of Maxillo-Facial Orthognathics, Graduate School of Dentistry, Tokyo Medical and Dental University.
Abstract:
The purpose of this study was to investigate the influence of 3,3-dimethyl-1-phenyltriazene (DMPT) on development of craniofacial structures in mouse fetus. (1) Pregnant C57BL/6 mice were treated with 30 mg/kg DMPT injection on days 10.5 approximately 13.5 of gestation. The fetuses were analyzed on day 15.0. The incidence of micrognathia was formed 100% in the treated group on days 10.5 and 11.0, and then decreased remarkably after day 11.5. This result suggested that the critical period of micrognathic development is days 10.5 approximately 11.0. (2) The fetuses, injected 30 mg/kg DMPT on day 10.5, were sacrificed on days 11.0 approximately 18.0. Their heads were used for the following histomorphological analyses: 1. clearing and Alcian blue-alizarin red double staining and 2. lateral graphic reconstruction using serial frontal sections. Dysmorphology of the anterior portion of Meckel's and nasal septal cartilage became evident after day 13.0, however, nasal capsule cartilage was hardly affected. It was concluded that hypoplastic Meckel's cartilage, caused by the administration of DMPT, induced mandibular dysmorphogenesis.
Insights
3,3-dimethyl-1-phenyltriazene (DMPT) exposure during critical gestational periods (days 10.5-11.0) in mice causes micrognathia. DMPT-induced hypoplastic Meckel
Area of Science:
- Developmental biology
- Teratology
- Craniofacial development
Background:
- Craniofacial development is a complex process susceptible to environmental influences.
- Understanding the impact of specific chemical exposures on fetal development is crucial for identifying potential teratogens.
Purpose of the Study:
- To investigate the teratogenic effects of 3,3-dimethyl-1-phenyltriazene (DMPT) on craniofacial development in mouse fetuses.
- To determine the critical developmental window for DMPT-induced micrognathia.
Main Methods:
- Pregnant C57BL/6 mice were administered DMPT (30 mg/kg) during specific gestational days (10.5-13.5).
- Fetal analysis included macroscopic examination, micrognathia incidence assessment, and histomorphological analysis (Alcian blue-alizarin red staining, serial section reconstruction).
Main Results:
- DMPT exposure on days 10.5-11.0 resulted in 100% incidence of micrognathia, identifying this as the critical period.
- Histomorphological analysis revealed dysmorphology in the anterior Meckel's cartilage and nasal septal cartilage after day 13.0.
- Nasal capsule cartilage remained largely unaffected by DMPT exposure.
Conclusions:
- DMPT administration during early gestation is a potent inducer of micrognathia in mouse fetuses.
- Hypoplasia of Meckel's cartilage is the primary mechanism underlying DMPT-induced mandibular dysmorphogenesis.
- The findings highlight the sensitivity of specific craniofacial cartilages to teratogenic insult during critical developmental windows.