RESUMO

Birds have enough conditions to be used as bioindicators for the presence of environmental contaminants. Notably, chlorpyrifos (CPF) remains extensively employed in Argentina, particularly in fruit plantations and livestock settings This study aimed to assess the potential impacts of CPF on common quail (Coturnix coturnix) embryos through external eggshell application during key embryonic stages (days 1, 4, and 14). Concentrations equivalent to those used in fruit applications, 5× and 10 × (38.4, 192, and 384 µg/egg), were employed. A 48% commercial formulation of CPF (Pirfos - Icona®) was utilized. An increase in embryonic deaths, as well as a statistical association between the degree of liver or kidney lesions and CPF concentrations was observed. The results suggest that CPF can induce embryotoxic effects with a single exposure to quail embryos and compromise the viability of the organisms. The study suggests a potential exposure risk for embryos through contact with the insecticide on the eggshell's exterior.

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RESUMO

Animals developed or in an embryonic stage, are constantly subjected to magnetic pollution generated by electrical and electronic devices. Several researches have used the bird embryo as an experimental model to evaluate the action of magnetic field (MF) and electromagnetic field (EMF). This study proposed to perform a morphometric evaluation in the embryos and in the blood vascular network of the yolk sac membranes (YSM) of Japanese quail (Coturnix japonica) exposed to the 60 Hz MF with two different intensities (0.16 and 0.65 mT). A total of 30 eggs were used, 10 eggs were used for each assay. Each assay formed a group (control group, group submitted to the MF of 0.16 mT and 0.65 mT). The images of the skeletonized vascular network of YSM were evaluated by two methods of fractal dimension: box-counting dimension (Dbc) and information dimension (Dinf). The embryos were evaluated by body mass, percentage cephalic length and body area. The fractal dimensions revealed no difference among groups. There were no significant differences in relation to embryonic body mass among groups. However, the embryos exposed to 0.65 mT MF presented a smaller embryonic body development (body area and percentage cephalic length). In conclusion, 0.16 mT and 0.65 mT magnetic fields were not able to generate significant effects on vasculogenesis and angiogenesis. However, the embryos exposed to 6 h of magnetic field with 0.65 mT intensity and 60 Hz frequency showed a decrease in embryonic body development.

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RESUMO

In birds, male embryo the gonads develop bilateral testes, in which both left and right sides produce functional spermatozoa, whereas female embryo, only the left gonad develops into a functional ovary. Estrogen plays a key role in avian sex determination in both sexes by binding to the estrogen receptor (ER). Surprisingly, chicken estrogen receptor (cER) mRNA is expressed in both sexes; moreover; its expression is only expressed in the left male gonad. The present study aimed to localize ER protein in the left gonad of male quail embryo using immunohistochemistry. The 8-day-old male quail embryos whose embryonic sex distinguished by gonadal morphology were studied. Histology of the left male gonad displayed thin cortex containing 1 to 2 layers of the germinal epithelium, while testicular cords were observed in the medulla. ER-immunoreactive cells were only found in the germinal epithelium but not in the medulla. Localization of ER was detected in the nucleus and cytoplasm of the germinal epithelial cells. The number of ER-immunoreactive cells counted in upper, lateral, and lower regions of the germinal epithelium was 18.20±1.892, 17.60±1.887, and 16.20±1.290, respectively. This study shows the first evidence for expression of ER protein in the left male gonad of the avian embryo, indicating that ER plays a role in avian gonadal sex differentiation.

En las aves, la gónada embrionaria en los machos se desarrolla bilateralmente, ambos testículos producen espermatozoides funcionales, mientras que en el embrión hembra, sólo la gónada izquierda se convierte en un ovario funcional. El estrógeno juega un papel clave en la determinación del sexo aviar, en ambos sexos, mediante la unión al receptor de estrógeno (RE). Fuertemente los receptores de estrógenos de pollo (cRE) el ARNm se expresan en ambos sexos; además, su expresión sólo se produce en la gónada izquierda del macho. El objetivo fue localizar proteínas del RE en la gónada izquierda de embriones de codorniz macho mediante inmunohistoquímica. Se estudiaron embriones de codorniz machos a los 8 días de edad, cuyo sexo embrionario se distinguió por la morfología de las gónadas. La histología de la gónada izquierda estuvo representada por la corteza delgada que contiene de 1 a 2 capas del epitelio germinal, mientras que se observaron cordones testiculares en la médula. El RE se encontró en células inmunorreactivas del epitelio germinal, pero no en la médula. Se detectó la localización de RE en el núcleo y el citoplasma de las células epiteliales germinales. El número de células RE-inmunorreactivas en las regiones superior, lateral e inferior del epitelio germinal fue de 18,20±1,892, 17,60±1,887 y 16,20±1,290, respectivamente. Este estudio muestra la primera evidencia de expresión de la proteína de RE en la gónada izquierda del embrión aviar macho, lo que indica que el RE desempeña un papel en la diferenciación sexual de la gónada aviar.

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