Introduction This second chapter deals with the second parts of the application of microscopic radioautography to some of the visceral organ systems. The visceral organs can be divided into 5 organ systems according to anatomy and histology, i.e., the digestive system, the respiratory system, the urinary system, the reproductive system and the endocrine system. Among of them the digestive system consists of 2 parts, i.e., the digestive tract and the digestive glands. The former consists of

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... e tube structures such as the oral cavity, the esophagus, the stomach and the intestines, while the latter consists of complicated glandular structures such as the large digestive glands , i.e., the liver and the pancreas, while the respiratory system consists of 2 parts, one the respiratory tract such as the nose, the pharynx, the trachea, the bronchus, and final essential part the lungs. This chapter deals with the digestive organs and the respiratory organs, respectively. Macromolecular synthesis in the digestive system The digestive system consists of the digestive tract and the digestive glands. The digestive tract can be divided into several portions, from the upper part to the lower part, i.e., the oral cavity, the pharynx, the esophagus, the stomach, the small and large intestines and the anus, while the digestive glands consist of the large glands such as the salivary glands, the liver and the pancreas and the small glands affiliated to the digestive tracts in the gastrointestinal walls such as the gastric glands including the fundic gland and the pyloric gland, the intestinal glands of Lieberkühn and the duodenal glands of Brunner. We have published many papers from our laboratory dealing with the macromolecular synthesis in respective digestive organs from the oral cavity to the gastrointestinal tracts and the digestive glands