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.
NASA was established in 1958 to keep U.S. space efforts abreast of recent Soviet achievements, such as the launching of the worldâs first artificial satelliteâ Sputnik 1 âin 1957. In the late 1950s and early 1960s, the two superpowers raced to become the first country to put a man in space and return him to Earth.