A mixed tideâtwo uneven tides a day, or one high and one lowâis also possible. Tides vary on timescales ranging from hours to years due to a number of factors. To make accurate records, tide gauges at fixed stations measure water level over time.
Top 10 facts about the world. Oligodendrocytes, also known as oligodendroglia, are a type of brain cell in the central nervous system that belongs to the glial cell family. The main purpose of glial cells is maintenance and support of nervous system cells.
1 Oligodendrocytes-neuroglial cells of ectodermal origin that myelinate axons in the central nervous system and forms the white matter of the central nervous system (unmyelinated axons are grey matter. 2  Astrocytes-star-shaped nutritive and supportive glia cells of the central nervous system.