Morphological and histological characterization of rectal gland in the brown banded bamboo shark (Chiloscyllium punctatum) from the Persian Gulf

Rectal gland is an important organ for osmoregulation in the sharks, and has species-specific features which are dependent on fish size. In this investigation, 36 individual of Brown banded Bamboo sharks (Chiloscyllium punctatum) were caught from Dervish's Creek located at the northern of Persian Gulf in both autumn and spring seasons. After weighting, biometry, sex determination and the numbering of sharks, the rectal gland were removed and weight were measured and then immediately fixed in Bouin’s solution. Histological sections of 5 micrometers were prepared and stained with Hematoxylin and eosin and then studied by using light microscope.The morphological results showed that about the size of the rectal gland, there was no significant difference between males and females (p>0.05) but the smaller sharks have larger rectal glands in proportion to their body size comperated to larger sharks (p<0.05). Also, it seems that the weight of rectal gland is not dependent upon sex and reproductive season. In addition, considering to the results of both seasons, we can conclude that the rectal gland weight of this species was independent of sex and breeding season. Microscopic results indicated that rectal gland had four structural regions: The capsule, outer parenchyma, inner parenchyma and central canal.