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 is the exploration agency of the Federal Government. NASA Earth observing satellites often open up new vistas for Earth science research. All are meant to explore the envelope of what is known and understood about the physical, chemical and biological processes of the planet.Learn more about Ocean Exploration at NASA.ooking at our Earth from space, it is obvious that we live on a water planet. Ocean covers over 70% of the Earth's surface and contains about 97% of the Earth's surface water. Life in the oceans can be found from the surface to the extreme environments at the bottom of the deepest submarine trench.