CHAPTER 21 - THE DIGESTIVE SYSTEM (III)

Abstract

This chapter discusses the liver and pancreas in association with the digestive system. In man, the liver arises as a diverticulum of the gut endoderm just anterior to the anterior intestinal porta. Cells proliferating from the diverticulum pass into the mesenchyme of the septum transversum and occupy the meshes of an already existing network of capillaries related to vitelline and umbilical systems of vessels. Simultaneously, there is an invasion of the same spaces by cells derived from the visceral mesothelium. Both kinds of cells together form the hepatic parenchyma. The liver is surrounded beneath its serous covering by a connective tissue capsule, formerly known as Glisson's capsule. At the hilum, this capsule penetrates into the organ, giving off septa. The lining of the gall-bladder is usually thrown into large folds, most of which disappear when the viscus is distended. The wall consists of four coats. The pancreas is a tubule-alveolar gland whose main duct opens into the duodenum.