RESUMO
The present study aimed to evaluate the teratological effects of gamma-irradiation during three intervals of gestation; pre-implantation, organogenesis and fetal periods in rats. Four groups of pregnant rats were used in this study; the first one [GI] served as control. The second [GII], third [GIII] and fourth [GIV] groups were subjected to whole body gamma-radiation at a sub-lethal single dose level of 4 Gy at the third day, 10[th] day and 14[th] day of gestation respectively. Pregnant rats were sacrificed at the 20[th] day of gestation, implantation sites, resorption, embryonic death, fetal death, growth retarded fetuses, external malformations and skeletal malformiation were recorded. The results showed that whole body gamma-irradiation caused resorption in the embryos of pregnant rats especially in those exposed during the pre-implantation period than the two other periods. The embryonic and fetal deaths were prominent in the fetuses maternally exposed to whole body gamma-irradiation during the organogenesis period. The highest percentage of growth retarded fetuses was found in fetuses maternally exposed to gamma-rays during the organogenesis period followed by fetuses maternally exposed to gamma-irradiation during the fetal period and then fetuses maternally exposed to gamma-irradiation during the pre-implantation period. The skeletal malformations as a result of gamma-irradiation were mostly represented in less ossification in the skull bones, less ossification in the vertebral centra and wavy ribs. The most affected fetal skeleton was perceptive in GIII [fetuses maternally exposed to gamma-irradiation during the organogenesis period] followed by GIl and then GIV