| Budget Amount *help |
¥3,600,000 (Direct Cost: ¥3,600,000)
Fiscal Year 2001: ¥1,500,000 (Direct Cost: ¥1,500,000)
Fiscal Year 2000: ¥2,100,000 (Direct Cost: ¥2,100,000)
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| Research Abstract |
We examined the morphological, functional and molecular abnormalities in the offspring of mice (B6C3F_1 and CB.17F_1) exposed to dioxins.
A single i.p. or p.o. administration of 100 or 50 ng of 2, 3, 7, 8-Tetrachlorodibenzo-p-dioxin per g of body weight was given to male mice, and mated with untreated female mice to examine the morphological and functional abnormalities in their offspring. On Day 18 of gestation, their fetuses and fetal appendages were removed by the cesarian operation. Implants, early deaths, late deaths, and the external abnormality of living fetuses were examined, and fetuses were resuscitated by pudding with tissue paper to check RDS (respiratory distress syndrome).
Up to now, we have gotten following results ; the incidence of implantation decreased significantly in the dioxin (100ng/g) treated group in contrast to control group. And significant increase of morphological anormalies (p<0.05) was observed in CB.17F_1 mice, but in B6C3F_1, an increase was marginal significant (p=0.055). The malformations observed in the dioxin treated group were dwarf, omphalocele, agnathy, cleft palate, kinky tail, short tail, agenesis of the testis, general edema, syndacryly, and in the control group were dwarf, Meckel diverticulum, open eye, and cleft palate.
Additionally, dose dependency (increasing incidence of early deaths, malformation and decrease of implantation, living fetus) was also observed in B6C3F_1 mice.
Furthermore, significant increase of functional defects like respiratory distress syndrome was observed in the F_1 fetuses of TCDD treated male mice of two different strains.
Increased incidence of molecular changes, i. e., length polymorphism of repetitive DNA sequences (pc-3) was detected but it was not yet significant at present. Large scale experiments are in progress.
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