The Teratogenic Effects of Monosodium Glutamate (MSG) on the Development of Chick Embryos

Objective: The present study was conducted to evaluate the toxicity and teratogenic effects of MSG in chick embryo development. Methods: Various concentrations of MSG solution, 1 mg, 1.5 mg, 2.5 mg and 3 mg of MSG/gm egg weight were injected into the fertilized hen’s egg at 21 hrs of incubation and further incubated until day 3, 6 and 10. The day 3 and day 6 were processed for serial section, while the day 3 was processed for total mount and day 10 were observed totally. Results: The effects of MSG were growth retardation, embryonic death and congenital malformations of several organs such as brain (rachischisis and anencephaly), eye (microphthalmia and anophthalmia), ectopiacordis, ectopia viscera, opening of posterior neuropore (spinal bifida) and under development of heart and viscerae. Conclusion: MSG produced congenital deformities and growth retardation in chick embryos which may predict to cause the same results to human embryos. Pregnant women should be advised not to consume MSG to avoid potential harmful effects to the unborn child

The Teratogenic Effects of Glyphosate Based Herbicide (GBH) on the Development of Chick Embryos

Objective: This study was conducted to investigate the teratogenic effects of GBH by using chick embryo as an animal model. Methods: The equal volume of 0.1 ml of 0.01%, 0.05%, 0.3%, and 0.5% w/v glyphosate solution were injected into yolk sacs of fertilized White Leghorn eggs at 21 h of incubation and repeated at the volume of 0.05 ml on the 3rd day of incubation. The embryos were observed for abnormalities on day 3, 6 and 10 of incubation. Results: The results showed that the mortality percentages increased as the concentration of glyphosate increased. Day 3 chick embryos showed retardation of development and several abnormalities, for instance, the irregular shape of the brain vesicles with an opening of anterior neuropore, small eye primordia with the optic cup and lens vesicle retardation, looser of the heart looping with dilated lumen, lesser number of branchial arches, absent of limb bud or tail fold. Day 6 chick embryos showed severe retardation of several organs. Microphthalmia, anophthalmia, ectopia cordis and ectopic viscerae were observed in day 6 chick embryos. On day 10, most embryos died earlier and living embryos showed normal external features but delayed ossifications which were significantly different from the control (P<0.05). Conclusion: Glyphosate was toxic to chick embryos which directly caused mortality and was also a powerful teratogen which caused growth retardation and malformations on day 3 and day 6 and skeletal alteration on day. The effects were predicted to occur in other embryos including humans. Pregnant women should avoid contamination with GBH especially in the first trimester of pregnancy

The Origin of Endoderm: Transmission Electron Microscopic Point of View

Objective: To show the transmission electron microscopic (TEM) evidence to confirm that the endoderm originates from the epiblast of the primitive streak or from other sources. Methods: 60 fertilized Leghorn hen’s eggs were used in this study by incubating the eggs for about 18-27 hours at 38°C, then the chick embryos of the primitive streak stage to 7-somite stage were further processed for routine TEM study at the region of the primitive streak. Results: The epiblast proliferates and accumulates to form the primitive streak at the midcaudal of the embryonic disc from 18-27 hours incubation which corresponds with the early third week of the human embryo. TEM evidence shows that the epiblast at the primitive streak is the stratified columnar type of epithelium while the hypoblast is the simple squamous and the mesoderm cells are irregular in shape. The process of gastrulation begins with the formation of the filopodia of the epiblast by numerous protrusions of the plasma membrane from lateral side of the cell. These structures initiate the separation of the contacted cells. The deepest epiblast cells separate first while the superficial epiblast cells exhibit the desmosome between the adjacent cells. The separated epiblast cells are bottle-shaped with numerous filopodia and gradually change the shape into round or oval cells which migrate in the space between the epiblast and hypoblast. Some of these migrate to the hypoblast and contact with the hypoblast, the mesoblasts lose the filopodia and gain more close contact to the hypoblasts which become a very thin sheet of cells. The facing cell membrane later gradually disappears and the mesoblast then occupies the region of pre-existing hypoblast. There is no evidence that the mesoblast displaces the pre-existing hypoblast laterally to form the extraembryonic endoderm. Conclusion: These are TEM evidences that the epiblast of the primitive streak separates and migrates to form the mesoblast and some contact with the hypoblast. The later process appeared to reveal that the mesoblast compresses the hypoblast until the facing plasma membrane disappears and occupies the region of the pre-existing hypoblast

The Teratogenic Effects of Antiepileptic Drug, Topiramate, on the Development of Chick Embryos

Background: Anti-epileptic drugs are known to be the risk of teratogenicity. Topiramate (TPM) is a new kind of such drug, for which no research has confirmed the incidence of producing congenital abnormalities. Objective: This study was conducted to study the teratogenic effects of TPM by using chick embryos as an animal model and the results can be compared to the human embryo of the same stage. Methods: Fertilized Leghorn hen eggs were injected in ovo with two concentrations of TPM, which were 10mg, and 20mg, in NSS at a volume of 0.1 ml into the yolk sac at 21 hrs of incubation and repeated injections at 72 hrs at a volume of 0.05 ml. The chick embryos on day 3, 6 and 11 of incubation were sacrificed and all living embryos were processed for total mount and serial section. Results: The mortality rate increased corresponding to the concentrations of TPM, and the embryonic stage. The total mount of day 3 showed major abnormalities of the eye and heart, such as microphthalmia and looser of heart looping. The serial section of day 3 showed opening of the anterior neuropore, ectopia viscerae and multiple malformations of the eye and heart. Day 6 chick embryos showed ectopia cordis and ectopia viscerae. Moreover, there were retardation and abnormalities of several organs such as eye, heart, liver, mesonephros and gonads. Day 11 chick embryos showed ectopia viscerae and several growth retardations, retardation of ossification of both limb bones and skull bones. Conclusion: This study showed that TPM might cause embryonic death, growth retardation and abnormalities of the eye, heart, an opening of the anterior neuropore and ectopia viscerae. This might indicate abnormalities to the baby born from mother with gestational epilepsy who was taking this drug continuously, and it might lead to spontaneous abortion or congenital anomalies of the fetus

Genetic differentiation of Anisakis species (Nematoda: Anisakidae) in marine fish Priacanthus tayenus from Gulf of Thailand

Members of the genus Anisakis are parasitic nematodes of the family Anisakidae. They are potential zoonotic parasites, causing anisakiasis in humans who consume raw or undercooked seafood (fish or squid) infected with the larvae of this nematode. In the present study, anisakid nematodes collected from the marine fish Priacanthus tayenus (Purple-spotted big-eye) caught from the Gulf of Thailand were examined morphologically and characterized genetically by DNA sequence analysis. Sequence data from the mitochondrial cytochrome c oxidase subunit II (mtDNA cox2) gene were used to identify these nematodes to species level and to evaluate the phylogenetic relationship among various taxa. All the 15 third-stage larvae of Anisakis nematodes investigated in this study belonged to the same genetic lineage as the A. typica species complex (named here as A. typica sp. T – T for Thailand). Eight mtDNA cox2 haplotypes were revealed in the 15 isolates of this Anisakis from Thailand. The mtDNA cox2 haplotypes of A. typica sp. T from Thailand were genetically distinct from those of the A. typica sensu stricto. Taxonomic description of this A. typica sp. T as a distinct species however awaits the availability of adult specimens

The Teratogenic Effects of Dichlorvos on the Development of Chick Embryos

Objective: The purpose of this study was to elucidate the teratogenic effects of dichlorvos on developing chick embryos. Methods: The fertilized Leghorn hen eggs were divided into two groups: the experimental group which was injected with 0.1 ml of 0.5% and 1% dichlorvos in normal saline and the control group which was injected with 0.1 ml of normal saline after 21 h of incubation. On day 3, 6, and 11, the embryos were collected for studying embryonic dead and abnormalities. Results: The results showed that the mortality rate increased with the increasing concentration of dichlorvos and time of incubation. The total mount of day 3 had only three primary brain vesicles, small and retarded primordial eye, dilated U-shaped heart looping, bifurcation of spinal cord and trunk when compared with the control. The results in the serial section of day 3 and 6 showed several abnormalities especially the retardation of eye and heart. Day 11 embryo revealed morphological anomalies including hematoma and bone deformation. Conclusion: Dichlorvos caused congenital abnormalities in chick embryos in 3 categories, the growth retardation, the malformations and the embryonic death which were predicted to cause the same results in contaminated humans. Dichlorvos exposure increases the risk of malformations and embryonic death. The present study revealed that dichlorvos was a powerful teratogenic compound and therefore its use should be limited and pregnant women should avoid contamination with dichlorvos especially in the first trimester