Histology of the digestive system of the black scorpionfish Scorpaena porcus L.

Abstract

      The present study is the first record of black scorpionfish digestive tract histology, suggesting that its histological features are mostly similar to those of other carnivorous fish and congruent to its feeding habits.
      The digestive systems of five specimens of the black scorpionfish, Scorpaena porcus L., from the eastern Adriatic Sea, were analysed histologically. The paraffin sections of oesophagus, stomach, intestine, liver, gallbladder and pancreas have been stained by hematoxylin – eosin technique in order to distinguish the main histological features of the digestive system in black scorpionfish. The wall of oesophagus and stomach is formed by four distinctive layers: the mucosa, the submucosa, the muscular and the outer layer. The wall of intestine and gallbladder consisted of three distinctive layers: the mucosa, the muscular and the outer layer. The mucosa is the innermost layer, which consists of two different layers: the epithelium and lamina propria. The submucosa is a layer of connective tissue with blood vessels and nerve fibres, and it has not been seen in the intestine and gallblader. In the oesophagus, stomach and intestine, the muscular layer consists of two layers of muscle fibres: circular and longitudinal. In the oesophagus the inner muscular layer consisted of longitudinally arranged striated, while the outer layer consisted of circular muscle fibres. The arrangement of muscular layers in the stomach and intestine is reverse. The muscular layer in the gallbladder is made of a single layer of smooth muscular tissue. The outermost layer of the upper parts of visceral organs is adventitia consisting of connective tissue. In the caudal parts of digestive tract, this layer is replaced by serosa. The liver consists of hepatocytes that are surrounded by mass of fat – storing cells. The arrays of hepatocytes are separated by system of sinusoidal capillaries. The pancreas consists of serous acini.