The effect of XXXX exposure on extraembryonic vascular development in the @entity1573 area vasculosa.

@entity851 @entity46455 @entity167 @entity35320 @entity26 @entity35319 @entity1573 @entity1881 @entity2827 @entity1068 @entity1968
The effect of @entity1068 ( @entity167 ) exposure on extraembryonic vascular development was examined using the @entity1573 embryo area vasculosa (AV) in shell-less culture. Embryos were placed in cultures at Hamburger Hamilton (HH) stage 11/12 and a single dose of @entity167 (10, 30 or 50%) was applied to the center of the blastodisc. Untreated/ @entity2827 -treated controls showed normal embryonic growth and well-developed extraembryonic vessels at 24/48 h of treatment. At doses of 30 and 50%, the mortality rate was significantly increased, and survivors demonstrated significant @entity851 and inhibition of normal vascular development in a dose-dependent manner. Immunostaining for @entity35320 ( @entity35320 ) showed that mesenchymal cells continued to differentiate into angioblasts to form blood islands, but their assembly into primitive vessels was perturbed in a dose-dependent manner. Northern blot analyses of basic fibroblast growth factor, @entity35320 , @entity46455 and @entity35319 mRNA expression supported these findings and showed a dose-dependent decrease in @entity167 -treated cultures compared to controls. Co-treatment with @entity1881 (0.05 M) or @entity1968 (10(-8) M) significantly decreased the mortality rate and improved both embryonic growth and extraembryonic vascular development in the cultures. On the other hand, almost all embryos treated with 10% @entity167 survived the first 48 h after treatment. However, the complexity of the vascular tree measured as the relative vasculogenesis index, the surface area of the AV and the mRNA expression of vasculogenic molecules were increased during the first 24 h. This acute effect disappeared 48 h after treatment and the vascular tree continued to develop parallel to the controls. No significant @entity851 was observed in this group. These results suggest that, in terms of extraembryonic vascular development, an early, single, low-dose @entity167 exposure may have an acute, short-term positive effect, whereas moderate- or high-dose @entity167 exposure may severely perturb this process disabling the necessary absorption of the nutrients for the embryo to develop properly. The mechanisms of action of @entity167 on extraembryonic vascular development may involve the establishment of reactive @entity26 species, resulting in the initiation of oxidative stress and perturbation of @entity1968 signaling and alterations in the expression of growth-regulatory vasculogenic factors and their receptors.
