Fig. 1

Human salivary gland features. A Schematic location of PG, SMG, SLG, and MSG in the oral cavity and the trigeminal nerve spreading postganglionic parasympathetic innervation structures of the head. B Schematic structure of one branch of human SGs, classification of different types of acini, innervation, blood supply (arteries), main excretory duct cells, and contribution of major and minor glands in resting or stimulating saliva flow