[show abstract][hide abstract] ABSTRACT: Rising trend of production and use of nanoparticles has increased the possibility of their release into the aquatic environments. Therefore, knowing toxic effects of these materials on aquatic organisms is of great importance. The objective of this research was to study the acute toxicity of colloidal silver nanoparticles (CAgNPs) through determining the lethal concentrations in the euryhaline teleost, Aphanius dispar. Toxicology experiments were conducted for 96 h in freshwater according to the OCED 203 standard protocol. Fish mortality was recorded every 24 h after exposure to different concentrations of CAgNPs and then the data were analyzed using the US EPA Probit analysis program. Based on the results, the estimated 96h LC50 of CAgNPs was 59.876 mg/L. Accordingly, the tested CAgNPs should be classified according to GHS (Globally Harmonized System of Classification and Labelling of Chemicals) as “category acute 3” for Aphanius dispar; this means that presence of CAgNPs in the environment of this fish is detrimental and therefore its release into the aquatic ecosystem should be carefully considered.
[show abstract][hide abstract] ABSTRACT: Purkinje fibers or Purkinje cardiomyocytes are part of the whole complex of the cardiac conduction system, which is today classified as specific heart muscle tissue responsible for the generation of the heart impulses. From the point of view of their distribution, structure and ultrastructural composition of the cardiac conduction system in the ostrich heart were studied by light and electron microscopy. These cells were distributed in cardiac conducting system including SA node, AV node, His bundle and branches as well as endocardium, pericardium, myocardium around the coronary arteries, moderator bands, white fibrous sheet in right atrium, and left septal attachment of AV valve. The great part of the Purkinje fiber is composed of clear, structure less sarcoplasm, and the myofibrils tend to be confined to a thin ring around the periphery of the cells. They have one or more large nuclei centrally located within the fiber. Ultrastructurally, they are easily distinguished. The main distinction feature is the lack of electron density and having a light appearance, due to the absence of organized myofibrils. P-cells usually have two nuclei with a mass of short, delicate microfilaments scattered randomly in the cytoplasm; they contain short sarcomeres and myofibrillar insertion plaque. They do not have T-tubules.
[show abstract][hide abstract] ABSTRACT: Much of our knowledge regarding vertebrate blood and blood cells is based on mammalian references. The critical study of fish blood is relatively new and comparatively few investigations have been published that focus on marine animals. The morphology of hemocytes (blood cells) of Himantura walga (Dwarf whipray) was characterized via light microscopy. Based on this characterization, we classified homocytes into 7 distinct cells: RBC, thrombocyte, lymphocyte, monocyte, heterophil, eosinophil and basophil. INTRODUCTION syringes by cardiac puncture. Smears were made, fixed
World Journal of Fish and Marine Sciences. 01/2012; 4:240-243.
[show abstract][hide abstract] ABSTRACT: Rays are common elasmobranches in the northern waters of Persian Gulf and Oman Sea that may have one or more mineralized serrated stingers on the whip-like tail. The stingers are covered by epidermal cells among which some can produce venom. When these animals are dorsally touched, the stinger can be introduced into the aggressor by a whip reflex mechanism of the tail when the pectoral fins are touched, causing severe mechanical injuries and inoculating the venom. The exact localization of the venom secretory cells in the stinger of different species is controversial, but it is known that the cells are preferentially located in the ventro-lateral grooves in marine stingrays. A comparative morphological characterization of the stinger epidermal tissue of different ray species in the northern part of Persian Gulf and Oman Sea was carried out in this study. EDTA was used for decalcification of stings and conventional histological processes were subsequently employed. The results indicated that structure of dermis and epidermis layers of stings in all species are similar to the structure of corresponding layers in other parts of fish's body. The results of the present study have shown that all examined species of Dasyatidae family, but not Myliobatidae and Gymnuridae families, had venom secretory cells. Distribution of venom secretory cells varies in each species and is often located around or inside the stinger ventro-lateral grooves. These differences among the stingers of various species may explain the envenomation severity in these species.
[show abstract][hide abstract] ABSTRACT: Stingrays are common inhabitants in the northern waters of the Persian Gulf and Oman Sea. In the present study, the clinical aspects of injuries induced in three patients bitten by stingrays in Hormozgan province waters were first examined. The LD(50) of crude venom extract obtained from the most common stingray in Hormozgan province (Himantura gerrardi) was then estimated by up-and-down dosing and double dose methods in mice. Third and finally, the cardiac symptoms induced by injection of the extract from the venomous spines were evaluated in rats. Intense pain was noticed in all human cases. Redness was observed in two cases, and spasm and seizure were each recorded in only one case. LD(50) of the venom extract in mice was about 100 mg kg(-1). The observed cardiac symptoms in rats included an increase in pulse rate and various changes in electrocardiogram (ECG) parameters such as T and Q values, and PR and RR intervals.
[show abstract][hide abstract] ABSTRACT: The chordae tendineae of the heart are collagenous strands which extend from the apical margin of papillary muscles of the heart to the various areas on the ventricular surface of the valve leaflets. They convey the contraction of the papillary muscles to the valve and so prevent the latter's eversion. Eight hearts of the ostrich were collected, opened the left side of the heart and the length of the chordae tendineae were measured. Macroscopically they had interconnection and attached directly to the free edge of the left atrioventricular valve or tricuspid. Routine paraffin sectioning with special staining method and transmission electron microscopy method was done. Our results manifested that the chordae tendineae basically was connective tissue and covered by endocardium. The core connective tissue of chordae tendineae in the proximal part was loose connective tissue and in distal parts was dense irregular connective tissue whereas in the middle part it was dense regular connective tissue.