Publication: Effects of in utero exposure to low dose ionizing radiation on development in the rat
Authors
Bruni, J.E. ; Persaud, T.V.N. ; Froese, G. ; Huang, W.
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Publisher
Murcia : F. Hernández
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DOI
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info:eu-repo/semantics/article
Description
Abstract
Most studies of in utero effects of ionizing
irradiation involve high doses and examination
at postnatal intervals. Little information is available
on the effects of low levels of ionizing radiation
on embryogenesis. The developmental effects of in
utero exposure to 50 cGy gamma radiation on
gestational day-9.5 was investigated using Sprague-
Dawley rats. Irradiated rats and appropriate controls
were killed at prenatal intervals of 4h, 48h and 10 days
after exposure. Fetuses were examined for abnormalities
and random samples of tissues were prepared for
microscopic study. With the exception of the neuroepithelium,
no histopathological changes were observed
in embryos 4h after exposure to 50 cGy. In irradiated
embryos, mitoses were reduced within the neuroepithelium;
pyknosis and some necrosis of cells were
apparent at this gestational interval. Among the gross
developmental abnormalities observed in embryos 48h
after irradiation, excessive flexion of the embryo and
abnormal flexion of the head were the only ones that
appeared to be radiation-induced. The mean numerical
score (47.310.2, controls; 42.410.1, irradiated) for 17
morphological parameters examined in fetuses at this
gestational period compares favorably with other
studies. Controls, however, showed greater variability in
the extent of development of their forebrain, olfactory
system, midbrain, hindbrain, and caudal neural tube. In
al1 cases, there was evidence of slower development in
these regions compared to their irradiated counterparts.
At term. no significant differences in litter size or
resorption rates were observed in irradiated animals
compared to the controls, but there was a higher
incidence of defective eye development, spinal curvature
and visceral anomalies. In utero exposure to 50 cGY
gamma-radiation during the period of early organogenesis
can produce some irreversible defects that are
discernible at term.
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