Impact of Environmental Contaminants on the Testes of Oreochromis niloticus with Special Reference to Ultrastructure of Spermatozoa in Lake Manzala (Egypt)

Abstract

IntroductionThe importance of Nile tilapia, Oreochromis niloticus in aqua cultures is due to its spreading in most countries of the world [1]. It breads in captivity and wide variety of water conditions [2]. Lake Manzalah (LM) is one of the most important lakes in Egypt that provides more than 70% of the total fishery of the country [3] and considered as a highly polluted with toxic heavy metals and pesticides due to progressive increase of industrial and agricultural drainage, as well as sewage out fall from the surrounding governorates [4]. The mean values of some heavy metals (Cd, Pb, Fe, Cr and Mn) recorded in LM were higher than the world permissible levels [5] and according to the Egyptian laws [6]. Such heavy metals are not lethal to fish, but concentrated in their flesh and create a hazard to the consumer [7,8]. Cd, Pb, Zn, and Cr are considered the main causes of pollution in aquatic ecosystem [9]. The serious effect of these metals is derived from their persistence, toxicity and bioaccumulation, and consequently exert dangerous problem to man [10]. Experimental studies on heavy metals proved that they could impair the respiratory functions of the gills; consequently death in fish is probably caused by tissue hypoxia [11]. Metals affect not only the fish morphology, but also all biological activities [12]. Among the heavy metals; Cd and Pb are the serious heavy metals that produce histopathological alterations including liver damage [13], respiratory dysfunctions [14], testicular and ovarian alterations [15][16][17]. These pathological alterations were primarily attributed to damage of cell membranes which allows higher uptake of Cd and Pb and thus the injury extends to more critical targets [18]. Many studies focused on bioaccumulation of heavy metals in fish and biological studies. Thus we aimed in this work to study the testicular histopathological alterations of Oreochromis niloticus using light microscope and the mature sperm using TEM. Materials and Methods Samples collectionSamples of water and 48 specimen of Nile tilapia, Oreochromis niloticus about 14-20 cm in length and 120-200 g in weight were collected from two areas; Demitta branch of RN at Mansoura city as a control site and LM as a polluted area during the spawning season from March-June and transported to the laboratory in tanks provided with oxygen pump. The fish were weighed, dissected and the testes were Abstract Background: Pollution of the aquatic environment by inorganic and organic chemicals is a major factor posing serious threat to the survival of aquatic organisms including fish. Lake Manzala (LM) is one of the Egypt's northern Delta Lakes situated on the Mediterranean Coast of the Delta. It is affected by drainage water polluted by different heavy metals that their concentrations exceed the maximum world permissible levels.

A study on the toxicity of 4-nonylphenol on the histopathology of testes of African catfish Clarias gariepinus (Burchell, 1822)

“…In the present study, testis shows the vaccuolation, structural changes in the germ cells such as sickle shaped germ cells and the rupturing of the germ cells. Similar observations were made by the Shalaby and Migeed, (2012) where they studied the impact of environmental contaminant on the testis of Oreochromis niloticus. Kumar et al, (2007) also reported the presence of large number of inter and intra tubular vacuoles, condensation of spermatogonic cells in the testis of Heteropneustus fossilis after exposure of liner alkyl benzene sulphonate.…”

Impression of Various Water Reserves on Reproductive Performance of the Nile Tilapia “Oreochromis niloticus”

“…The seasonal investigations of both females and males GSI organized as the highest values were in spring, followed by summer, while the lowest female GSI values were in winter, and in autumn for males. Such results are in accordance with those of many studies (Njiru et al, 2006;Shalaby & Migeed, 2012;Hamed et al, 2016;Khallaf et al, 2020). This study also agrees with El-Kasheif et al (2013) and Khallaf et al (2020) concerning the fact that the female Nile tilapia individuals have higher value of GSI than males at constant age, length and season; besides, the seasonal variations of both O. niloticus sexes following nearly the same trend.…”

Evidence of the sterility of allotetraploid Cobitis loaches (Teleostei, Cobitidae) using testes ultrastructure

“…Necrosis has been characterized as passive, accidental cell death resulting from environmental perturbations or as a well‐regulated process activated by rather specific physiological and pathological stimuli (Proskuryakov, ). Many studies have shown that several factors, for example, pollution and heavy metals, induce necrotic changes in the testes of fish (Shalaby & Migeed, ) and mammals (Niknafs et al., ). In this process, characteristic nucleus changes, defined as pyknosis, are commonly observed and include nucleus contraction and chromatin condensation.…”