Effect of retinoic acid upon the chick embryonic morphogenetic systems. I. The embryotoxicity dose range (original) (raw)
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The Effect of Retinoic Acid on Development of Chicken Embryos
The Effect of Retinoic Acid on Development of Chicken Embryos
Background and aims. Retinoic acid (RA) is important morphogen for promoting normal vertebrate development, its work in critical gradient in most organs and tissues. Exogenous of RA can cause malformation in these organs and tissues. The current study aimed to find out the effect of application of different concentrations 6 ,10mg/ ml of retinoic acid dissolved in dimethyl sulphoxide (DMSO) on chicken development at different embryonic stages. Methods. Fertile domestic Gallus gallus eggs sullied from local poultry farm, eggs were cleaned and sterilized, then divided into two groups of experiments, one group for each concentration. Each experiment contains three groups, 10 eggs for each. These groups repeated four time for four different stages HH8, HH10, HH15 and HH18. Eggs were incubated in the incubation for require stage, then removed from incubation and injected with RA or (DMSO) in air sac or kept without injection as untreated control, then eggs were incubated for another 24 h. Eggs were opened after 24 and 48 h of incubation, survive embryos were collected and evaluated morphologically and histologically. Results. The study showed that RA cause general growth retardation. In addition, it causes, microcephaly, cranial bifida, cardiomegaly, forelimb induction, straight trunk. The degree of malformation depended on the developing stage and RA concentration, were malformation increases with high concentration and early stages. Significant effects observed in embryos treated with 10mg/ml at early stage. Moreover, effects of RA in HH8 and HH10 was sharper than that observed at embryos injected at HH15 and HH18 in two concentrations. Conclusion. This study demonstrates that exogenous RA treatment at doses above those necessary to ensure normal embryonic development results in severe abnormalities. This suggests that the embryonic response to rheumatoid arthritis is extremely sensitive, particularly during fetal neurogenesis.
Development
The aim of these experiments was to determine the endogenous distribution of retinoic acid (RA) across a wide range of embryonic stages in the chick embryo. By high pressure liquid chromatography, it was revealed that didehydroRA is the most prevalent retinoic acid in the chick embryo and that the tissues of the stage 24 embryo differed widely in their total RA content (didehydroRA + all-trans-RA). Some tissues such as the heart had very little RA and some such as the neural tube had very high levels, the total variation between these two being 29-fold. We showed that these tissues also synthesised RA and released it into the medium, thus validating the use of the F9 reporter cell system for further analyses of younger staged embryos. With these F9 cells, we showed that, at stage 4, the posterior end of the embryo had barely detectably higher levels of RA than the anterior end, but that a significant level of RA generation was detected as soon as somitogenesis began. Then a sharp on...
Development (Cambridge, England), 1998
The aim of these experiments was to determine the endogenous distribution of retinoic acid (RA) across a wide range of embryonic stages in the chick embryo. By high pressure liquid chromatography, it was revealed that didehydroRA is the most prevalent retinoic acid in the chick embryo and that the tissues of the stage 24 embryo differed widely in their total RA content (didehydroRA + all-trans-RA). Some tissues such as the heart had very little RA and some such as the neural tube had very high levels, the total variation between these two being 29-fold. We showed that these tissues also synthesised RA and released it into the medium, thus validating the use of the F9 reporter cell system for further analyses of younger staged embryos. With these F9 cells, we showed that, at stage 4, the posterior end of the embryo had barely detectably higher levels of RA than the anterior end, but that a significant level of RA generation was detected as soon as somitogenesis began. Then a sharp on...
The effects of all-trans retinoic acid on blood cells in rat's embryo
Pakistan journal of pharmaceutical sciences, 2009
All-trans retinoic acid (ATRA) has beneficial and teratogenicity effects when used in a variety conditions. The objectives of this study were to determine the effects of ATRA on the Progenitors of red blood cell and platelets in rat's embryo. Single oral dose (100 mg/kg) of ATRA was administered to rat on gestation day (GD) 10 and fetuses were observed on GD 18 and compared with untreated group. In the experimental embryos of GD 18, the mean number of red blood cells (RBC, 10.5%) and platelets number (15%) were decreased. There was a significant relationship in RBC and platelets count. The mean diameter of RBC and nucleated red blood (NRBC) were compared in two groups. There was no significant relationship between experimental and control groups, except in NRBC diameter. Thus, the present data shows that ATRA may have negative effects on proliferation, differentiation and maturation of erythroid cells and platelets, without having any deleterious effects on the dimenation of RBC.
The role of retinoic acid in embryonic and post-embryonic development
Proceedings of the Nutrition Society, 2000
Retinoic acid (RA) is the bioactive metabolite of vitamin A (retinol) which acts on cells to establish or change the pattern of gene activity. Retinol is converted to RA by the action of two types of enzyme, retinol dehydrogenases and retinal dehydrogenases. In the nucleus RA acts as a ligand to activate two families of transcription factors, the RA receptors (RAR) and the retinoid X receptors (RXR) which heterodimerize and bind to the upstream sequences of RA-responsive genes. Thus, in addition to the well-established experimental paradigm of depriving animals of vitamin A to determine the role of RA in embryonic and post-embryonic development, molecular biology has provided us with two additional methodologies: knockout the enzymes or the RAR and RXR in the mouse embryo. The distribution of the enzymes and receptors, and recent experiments to determine the endogenous distribution of RA in the embryo are described here, as well as the effects on the embryo of knocking out the enzym...
The International journal of developmental biology, 1993
Full primitive streak stage chick embryos, cultured in vitro for 20 h in the presence of 10(-9) to 10(-7) moles of retinoic acid (retinol, all-trans), exhibit increasing extent of malformations. RA causes caudalization, suppression of telencephalon, formation of open and enlarged neural tube in the regions of midbrain, hindbrain and spinal cord, failure of fusion of heart tubes, and gives rise to winged or diffused, and even supernumerary somites. Extreme abnormalities include failure to form the head fold and foregut. Abnormal embryos were graded according to Rao and Chauhan (Teratology 4: 191-198, 1971), and we find that the larger the severity of malformation, the smaller the size of total cell population and blastoderm area. Concomitant to caudalization, retinoic acid suppresses the cell population growth.