Histological study of hepatopancreas of Litopenaeus vannamei during cultural period

Objective: Litopenaeus vannamei (white leg shrimp) is a variety of prawn of the eastern Pacific Ocean and is the major species of farmed shrimp. Hepatopancreas is a vital and major organ of decapods including prawns that combines the functions of liver, pancreas and intestines in vertebrates. Its functions are storage of lipids, glycogen, minerals and other nutrients. Its function changes in some periods of prawn’s life and these changes reflect directly in the histological structure of the hepatopancreas. In this study, histology of hepatopancreas in Litopenaeus vannamei during cultural period is investigated. Method & Materials: In this study 60 post larvae of Litopenaeus vannamei in three different ages (below 0.5g, 0.5 – 1 g and more than 1 g) were caught from a farm in site Delvar2 located in 35 km east of Bushehr. After fixation in Davidson’s solution, weighing and biometry, the samples were processed by standard and routine paraffin embedding method and then sectioned at 5 μm. Tissue sections were stained with H&E and PAS and examined under light microscope. The micrometric study was carried out by calibrated ocular lens. Results & Conclusion: Microscopical studies showed that different kinds of hepatopancreatic cells including E, B, R and F cells were existed in Litopenaeus vannamei based on morphological structure. Size and shape of tubules and cells were calculated. There were few tubules in the hepatopancreas of the first group (below 0.5g prawn) but the tubule diameters and cell sizes were similar to those of the second group (0/5-1g prawn). It was noted that with the increase of body weight from group 2 to 3 there was a great increase in the number and size of tubules and also in the size of cells that this increasing was significant statistically. Histometrical studies indicated that tubule diameters in groups 1, 2 and 3 were 70.44 ± 3.12 μm, 68.56 ± 3.19 μm and 100.89 ± 3.97 μm, respectively and thickness of tubular epithelium were also 27.22 ± 1.36 μm, 26.44 ± 0.87 μm and 31.00 ± 1.05 μm, respectively. None of the E, B, R and F cells had positive reaction with PAS staining which show no glycogen storages were existed in different cells. Finally it can be concluded that there is a species-specific in hepatopancreas

کلیدواژه ها:

Hepatopancreas ، prawn ، Litopenaeus vannamei ، Histology ، Histometry