Comparative Histological, Histochemical and Ultrastructural Studies on the Liver of Flathead Grey Mullet (Mugil cephalus) and Sea Bream (Spams aurata)

The liver is one of the digestive glands that composed of parenchymal cells and lattice fibers. It plays a prominent role in metabolism and acts as storage center for many substances. The histological and histochemical distribution of mucosubstances as well as the ultrastructural characteristics of liver in Mugil cephalus (flathead grey mullet) and Spams aurata (sea bream) liver were investigated to compare between the histological characteristics of the livers of twoteleosts fishes with different feeding habits. Samples of liver from the investigated species were removed and processed for light and transmission electron microscopy. Histologically, the hepatic parenchyma of flathead grey mullet is consisted of hepatocytes which are radially arranged around the central vein interconnecting laminae of two cell thickness, hepatic triad at the portal area and narrow straight sinusoids separating each lamina. The liver tissue of Sparus aurata is consisted of hepatocytes which lie in anastomosing laminae around the central vein with the bile canaliculi intercellularly situated. The hepatopancreas in Sparus aurata has an acinar arrangement separated from hepatic parenchyma by a thin layer of connective tissue. Histochemically, the hepatic cells in Mugil cephalus are moderately positive to periodic acid schiff and alcian blue reactions, while the hepatocyte of Sparus aurata are weakly positive to these stains. The histological structural arrangement of hepatic parenchyma of. Mugil cephalus resembles that described in mammalian liver. Mugil cephalus appeared to be higher phylogenetic status than that of Sparus aurata.