Department of Teratology
Laboratory of Embryogenesis
Research topics
- Investigation of orofacial clefts;
- investigation of other developmental defects;
- investigation of experimental and clinical/epidemiological aspects.
Harmful external factors and a genetic predisposition are sought in clinical/epidemiological studies of developmental defects. Suspected external factors are tested experimentally in an animal model – chick embryogenesis.
Previous investigations in the Department have detected significant differences in the incidence of orofacial clefts between Czech districts during the last 30 years. The analysis of natality data from the Czech Republic has revealed that the number of newborn boys was higher than that of girls in each month from 1950 to 2005.
Experimental model – developing chick embryo.
(A) The injection of a test substance into the amniotic sac of a day 3 chick embryo in ovo. (B) Unilateral cleft beak in a day 9 chick embryo induced by the intra-amniotic injection of hydrocortisone on day 4 of incubation.
Orofacial clefts in man.
(A) The mean incidence of orofacial clefts in the districts of the Czech Republic during 1983–1997. (B) Basic types of orofacial clefts in man. CL – cleft lip and jaw unilateral, CLP – cleft lip and palate unilateral, CP – isolated cleft palate. The CL and CLP can also affect both the right and left side - CL bilateral and CLP bilateral, respectively.
The only exception was November 1986, when the number of newborn boys was significantly reduced. This has been explained by a selective negative impact of the Chernobyl accident in April 1986 on male fetuses during the 3rd month of their prenatal development. The correlation between the numbers of missing boys with the radioactivity levels has suggested that I-131 probably played the most important role, being taken-up by the fetal thyroid gland during saturation by iodine at the onset of its function in the 3rd month of human prenatal development. Experimental testing (see Fig. 1) of embryotoxic factors on the developing chick embryo) has determined the embryotoxicity ranges of more than 150 chemical substances and allowed for the estimation of embryotoxicity ranges for humans. We have shown that the upper second incisor originates from the fusion of two components in human embryos. These two components presumably do not fuse in patients with a jaw cleft; consequently, their upper lateral incisor can be duplicated, hypoplastic or missing.
