Histopathological Alterations due to the Effect of Lead Nitrate on the Testis of Freshwater Fish , Channa Striatus ( Bloch , 1793 )

The present study examined the histopathological effect of lead nitrate on the testis of fish (Channa striatus). Fishes having average length 20-25 cm and weight 50-60 g were distributed into four groups. The fishes of group I were kept as control, while II, III and IV were exposed to sub lethal concentrations (8, 18 and 28 mg/l) of lead nitrate for 30, 60 and 90 days. Examined sections revealed that the testis of C. striatus had damaged wall of seminiferous tubules, disorganization of seminiferous tubules, clustering of seminiferous tubules, deshaped and damaged seminiferous tubules, indistinguishable leydig’s cells, reduction in the number of leydig’s cells, necrosis, vacuolization, centralization of spermatozoa and reduction in the number of spermatozoa. The result of the present study clearly indicates that testicular histopathological alterations depend on duration of exposure and concentration of lead nitrate on the testis of Channa striatus. Article History Received: 23 May 2018 Accepted: 07 August 2018

introduction At present a large amount of metals are introduced through human activities into the natural environment.Globally, heavy metal pollution is becoming a serious issue of increasing concern to the survival of living organisms, including fish.Cadmium, mercury and lead are toxic to most aquatic organisms even in low concentrations 1 that produce histological alterations including liver damage 2 , respiratory dysfunctions 3 , testicular and ovarian alterations 4,5,6 .From recent few years, lead has gained considerable attention among the scientific community due to its potential human health hazards 7 .Popularity of lead is due to its dense ductile, highly malleable and corrosion resistant properties 8 as it is used in manufacturing of storage batteries, paints, dyes, pigments, coloured inks, pipes, soldering materials, cement manufacturing, mining, smelting, etc. 9 .Histopathological studies are being widely used as reliable biomarkers for determining the health of the contaminants exposed fishes 10,11 .These pathological studies indicated the damage of cell membranes which increases the injury to more critical targets 12 .Lead is also known to accumulate in different tissues in fishes 13 .Reproductive impact of lead exposure is spreading worldwide 14 almost affecting all characteristic of reproduction 15 .Therefore, the present study was carried out to investigate the testicular SHARMA, Curr.Agri.Res., Vol.6(2) 213-217 (2018) histopathological alterations in Channa striatus, induced by chronic exposure to lead nitrate.

materials and methods
Live specimen of fish, Channa striatus (average length 20-25 cm and weight 50-60 gms) were collected from different fish markets of Bhopal, Madhya Pradesh for experimentation.Fishes were divided into four groups as Group I, Group II, Group III and Group IV, and were exposed to sub lethal concentrations (0, 8, 18 and 28 mg/l, respectively) of lead nitrate (Ranbaxy India Ltd.) for a total period of 90 days.Exposure concentration was decided on the basis of 96 hrs LC 50 value of lead nitrate.LC 50 values at 95% confidence limits were calculated by using the software "Trimmed Spearman Karber method", version-1.5 16for different exposure period.To maintain apposite lead nitrate concentration throughout the experimentation duration of 90 days, water of each aquarium was changed on every alternate day.At regular interval of 30 days (at the end of 30 th , 60 th and 90 th days of experimentation), fishes from each groups were harvested, and the testis of all the four groups were removed aseptically.Tissues were preserved in aqueous Bouin's fixative for 48 to 72 hours 17 .After fixation, 5-6 μm thick sections were cut with the help of rotatory microtome and stained with Ehrlich's haematoxylin and eosin (H&E) for histopathological examination.

results
Histological sections of the testis of the experimental fishes are shown in Fig. 1 to Fig. 10.Histological sections of testis of control fish (Group I) showed typical histological picture similar to that of a normal fish, characterised by a number of seminiferous tubules irregularly arranged inside and spermatozoa in the germinal epithelium (Fig. 1).In case of Group II fishes, damaged walls of seminiferous tubules and indistinguishable leydig's cells on 30 th day (Fig. 2), disorganization of seminiferous tubules, vacuolization and indistinguishable leydig's cells on 60 th day of lead nitrate exposure (Fig. 3), while disorganization of seminiferous tubules, deshaped seminiferous tubules, necrosis and centralization of spermatozoa on the 90 th days of exposure (Fig. 4) were observed.Deshaped and damaged seminiferous tubules, clumping of seminiferous tubules, necrosis and indistinguishable leydig's cells on 30 th day (Fig. 5), while deshaped seminiferous tubules and necrosis on 60 th day (Fig. 6) and damaged walls of seminiferous tubules, centralization of spermatozoa and disappearance in the number of leydig's cells on the 90 th day of lead nitrate exposure (Fig. 7) were observed in case of Group III fishes.In case of Group IV fishes, the common histoarchitectural alterations observed on the 30 th day of lead nitrate exposure were clustering of seminiferous tubules, disorganization of seminiferous tubules, damaged walls of seminiferous tubules and centralization of spermatozoa (Fig. 8).The alterations were more severe as disorganization of seminiferous tubules, deshaped and damaged walls of seminiferous tubules, centralization of spermatozoa, severe reduction in the number of spermatozoa and indistinguishable leydig's cells on the 60 th and 90 th days (Fig. 9 & 10, resp.) were observed.

Discussion
Similar results were seen by 18 in case of Lepomis macrochirus exposed to endosulfan for 24, 48, 72, 96 hr, 1 and 2 week periods.The histopathological alterations in testes of fish showed connective tissue breakage, dilation of lumens, reduction in the size of primary spermatogonia, breakage of primary spermatocyte walls, greater increase in the size of seminiferous tubules and lumens, damaged sertoli cells and spermatids, damaged primary spermatogonia, decrease in the number of spermatozoa and spermatids, disruption of seminiferous tubule walls and disorganised structure of the testis.Cytolysis, vacuolation in seminiferous tubules, disorganized testicular architecture and extensive damage to germinal epithelium, necrotic cells and connective tissues in the testis of airbreathing fish, Heteropneustes fossilis due to the exposure of cadmium chloride for 45 days was also reported by 19 .Loosening and indistinguishable arrangement of tissue, disorganization of the lobules, disintegration of the spermatogonia and interstitial tissue, epithelial vacuolization, disorganization of germ cells, reduction in the number of spermatogonia in the testis of African catfish Clarias gariepinus exposed to 0.05 mg/l of mercuric chloride for 60 days was observed by 20 .It is construed from our study that the testicular histopathological alterations increased in proportion to the increase of lead nitrate concentration and length of period of intoxication in Channa striatus.

Conclusion
From the present study it is concluded that the extent of histological changes in the testis of Channa striatus not only depends on the concentration of lead nitrate but also on the duration of exposure.