Surface coating of the tooth is the hardest substance in the human body. This can be explained by the high degree of mineralization - the inorganic content in the enamel reaches 97%, with the water content up to 3%.
A liver with a duct system and a gallbladder develop from the hepatic diverticula of the ventral endoderm of the primary midgut. The onset of liver development is the 4th week of the intrauterine period. Future proximal bile ducts form from the proximal diverticulum, and the hepatic beams from the distal duct.
Hepatic lobule is a morphofunctional unit of the liver. In the center of the lobule is the central vein. Central veins, connecting with each other, eventually fall into the hepatic veins, the latter, in turn, flow into the lower vena cava.
The liver is the largest organ of man. Liver functions are diverse. It participates in the processes of digestion, hematopoiesis and performs numerous functions in the metabolism.
Human saliva is a secret that is secreted by salivary glands (large and small). The total volume of saliva produced during the day ranges from 1,000 to 1,500 ml (pH 6.2 - 7.6).
The structure of human salivary glands lies in dividing them into alveolar, tubular and alveolar-tubular. They represent a well-developed system of ducts that connect to a large excretory duct.
There are mucous, serous and mixed small salivary glands that lie singly and in groups in the submucosa, in the thickness of the mucous membrane and between the muscle fibers in the oral cavity of the oropharynx, the upper respiratory tract.
Starting from the 20th day of intrauterine development, the intestinal endoderm in the fetus's body contracts into the tube, forming the primary gut. The primary intestine is closed in its anterior and posterior parts and is located anterior to the chord.
