Sialolithiasis (sigh a lo THIGH a sis) is a condition where tiny salivary stones form in the glands. The stones, called sialoliths, are made of calcium. Some stones do not cause any symptoms, but some stones block the ducts. The saliva flow is partially or completely stopped.he three major salivary glands are the parotid gland, submandibular gland (also called the submaxillary gland), and sublingual glands. Saliva drains into the mouth through small tubes called ducts.
NASA facilities. NASA facilities exist across the United States, but also across the world. NASA Headquarters in Washington, DC provides overall guidance and political leadership to the agency. There are 10 NASA field centers, which provide leadership for and execution of NASA's work.
Yet these locations are also home to vital parts of NASA. Spread out from coast to coast, NASAâs centers and facilities are as diverse as the many different elements of the agencyâs missions. Thatâs no coincidence â each location is home to different areas of expertise, supporting different elements of those missions. Today, for example, Stennis Space Center in Mississippi is conducting rocket engine testing in support of NASAâs exploration mission.