Macro and microscopic structure of the digestive system of Octopus vulgaris From Alexandria water on the Mediterranean Sea

Abstract

The present work deals with the macroscopic and microscopic anatomy of Octopus vulgaris from Alexandria water on the Mediterranean sea. The digestive system is formed of the buccal mass, oesophagus, crop, stomach, caecum, intestine and rectum. The associated glands included the anterior and posterior salivary glands, liver and digestive duct appendages (Pancreas). In the present study, the structure of the buccal mass, with the upper and lower jaws has been described. Also the radular teeth, which are specific for their morphology and considered of taxonomic evidence for different octopod species, have been described. The oesophagus enters the crop on its right side approximately one third of the way from its anterior end. Musculature and lining epithelium of the two regions have been studied. The stomach is a region where the grinding of food occurs so that its lining epithelium is covered by thick layer of cuticle. The caecum is a coiled organ which lies below the stomach and has primary and secondary leaflet-like structures. Secretory cells are found between the columnar cells which form the lining epithelium. The intestine is a long tube, which is followed by short rectum, and has internal folds with scattered mucous cells between the columnar epithelial cells. The rectum has no mucous cells and its lining epithelium is covered with a thin layer of cuticle. The anterior salivary glands are smaller in size than the posterior ones and have two types of secretory cells like the posterior salivary glands. The digestive gland is a large grayish cigar-shaped organ, consisting of two fused lobes. It has two types of cells, big vaculated cells and small triangular ones. The pancreas lies around the two digestive ducts and forms a small wedge-shaped appendages, each is formed of a single layer of short columnar cells.