In ovo toxico-teratological effects of aluminum on embryonic chick heart and vascularization.

In spite of extensive research and persistent arguments, the mechanism of aluminum (Al) toxicity is still obscure. It is firmly established that aluminum is a potent neurotoxicant. So, the aim based on is aluminum damage chicken heart, as well as the vitelline circulation. In the first 3 days of incubation (D0-D2), 1.0, 2.0, or 4.0 mg aluminum chloride/0.3 ml avian saline was injected into the center of each viable fertilized egg yolk (AL1, AL2, and AL3 groups, respectively). Control eggs were either uninjected (AL0) or injected (ALS, 0.3 ml saline). Crown rump length was significantly decreased, while, embryonic mortalities, growth delay, as well as congenital heart defects were increased in the eggs injected 2.0 or 4.0 mg of Al. Although no relationship is clear about the embryonic mortality induced by Al in chicken embryos to the dose concentration, the higher mortality occurs in early developmental stages in developing chick embryos. Furthermore, chick embryos exposed to 4.0 mg/Al showed a high incidence of defects of ventricular septation and ventricular myocardium. Configuration and density of branched vitelline vessels were also significantly deteriorated after injection with 4.0 mg/Al. It concluded that Al is a cardiac teratogen for a chick in a dose-dependent way. These data highlight a novel approach for aluminum in congenital cardiovascular defects. Therefore, further research is needed to explain the teratogenicity of Al on the embryonic heart development.

Ultrastructural study of the lateral line neuromasts in tadpoles of Saudi Bufo dhufarensis and Rana ridibunda.

Neuromast (hair cells) structure in Bufo dhufarensis and Rana ridibunda larvae was observed by Scanning Electron Microscopy (SEM). Neuromasts were found arranged in one well-defined line in the head, body, and tail regions forming the lateral line and also found haphazardly scattered in most of the body parts. Their number was significantly high in the head region, and then it gradually decreased along the posterior end of the body. The structure of neuromasts in these three regions was basically similar for each species. In Rana, neuromasts were found few in number, either spherical or oval in shape lacking hair-like structure except in the tail region where hair cells were found. While in Bufo, neuromasts were numerous. Long kinocilia and many stereocilia were found in the neuromasts. Kinocilia were either solitary or in clusters. In addition to the main functions of the neuromasts we discovered a new function which was not found in previous researches, neuromasts were also used to remove any attached object on the tadpole's skin, by directing the kinocilium to the object thing and rolling onto it then detaching it outwards.