COMPARATIVE HISTOMORPHOMETRICAL STUDY OF GILL IN MATURE AND IMMATURE SILVER CARP  

This study was conducted on 10 immature silver carps with mean body length and weight about 10.95± 0.36 cm and 12.02 ± 1.08 gr and 10 mature silver carps with mean body length and weight about 41.4±1.07 cm and 1.5± 66.6 gr, respectively to evaluate the morphology and morphometric measurements of gills in this species. Grossly gills consist of four gill arches within operculum which located on either side of the pharynx. Freshly this organ appears to be bright red in color. Samples of gills were harvested as 0.5cm in diameter and fixed in Formalin 10% solution, then the routine tissue processing steps were performed and samples were cut into 5 to 6 µm in diameter and finally were stained with hematoxylene & eosin and acid Schiff solutions. Micrometric studies on the thickness of epithelial tissue covering the primary lamellae and gill rakers at both right and left sides in both mature and immature fishes, doesn't show significant differences. In mature fishes, the epithelial covering of gill rakers was measured thicker in apical area comparing to other parts. The results also revealed that the number of orifices of gill raker gap decreased with fish's weight but larger in diameters in both mature and immature fishes. The number of mucous cells in club-shape of primary lamellae was much greater in number than in the other parts which reflects more mucous secretion in these areas. The covering epithelium of lamella in this specific species, doesn^'t show any difference with other fishes in the family. The only difference was in the amount and length of the gill rakers.

Keywords: Histology, Silver carp, Gill, Immature, Mature