ABSTRACT
The echinoderm digestive system is conspicuously developed, being the most prominent system of the individual. The digestive system is thus surrounded by coelomic fluid. The digestive system is simple in shape in most echinoderms, being a tubular duct looping in the general body cavity or a bag-like system taking up almost the whole body cavity. The development of the part of the hemal system associated with the digestive system differs greatly depending on whether Asterozoa or Echinozoa are considered. Numerous coelomocytes occur in the lumen of the digestive hemal system, the digestive epithelium and the connective tissue layer of the digestive tract of all echinoderms except asteroids. The occurrence of coelomocytes inside the gut wall of asteroids has never been demonstrated. The inner basal lamina is located under the digestive epithelium, the outer one is located between the connective tissue layer and the muscle layer or the peritoneal lining when the muscles are lacking.
