ISSN 2756-3707
International Journal of Histology and Cytology ISSN 2447-9535 Vol. 2 (2), pp. 109-118, February, 2015. © International Scholars Journals
Full Length Research Paper
A study of the effect of zinc on the histological structure of liver in Nile tilapia, Oreochromis niloticus
Abdel-Warith, A. A.1*, Younis, E. M.1, Al-Asgah, N. A.1, and Wahbi, O. M.2
1Department of Zoology, College of Science, King Saud University, Riyadh, Saudi Arabia.
2Fish Reproduction Lab, National Institute of Oceanography and Fisheries, Alexandria, Egypt.
*Corresponding author. E-mail: [email protected].
Accepted 11 September, 2014
Abstract
In the present study the toxic effects of zinc (Zn) on the liver structure of Nile tilapia, OREOCHROMIS NILOTICUS were investigated. Additionally, we estimated whether Zn concentration and exposure period influence the degree and nature of histological changes in the liver of exposed fish. Two hundred and forty fish (the average weight was 24.30± 2.85 g) were distributed randomly in twenty four glass aquaria (80 L) with stocking density of 10 fish for each. The aquaria were divided into two groups: the first group was exposed to 2, 4 and 6 mg/L of ZnCl2 which represent 0.25, 0.50 and 0.75 of Zn LC50 respectively for one week (short exposure period); while the second group was exposed to the same concentrations of ZnCl2 with the same replicates for 4 weeks (long exposure period). In addition, control group were not exposed fish to ZnCl2 (0.00 LC50) were stocked with three replicates for each period. Fish mortality was significantly increased in a dose-dependent manner, without any significant effect of the exposure duration. Histological changes in the liver included hepatocyte degeneration, nuclear pycnosis, cellular swelling, and congestion of blood vessels. There was a marked difference in these changes among the different treatments of Zn concentrations in addition to the intensity of histological changes were however influenced by the extent of exposure period.
Key words: Nile tilapia, Oreochromis niloticus, liver, histological changes, LC50 of Zinc.