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.
Each oligodendrocyte can supply myelin for several axons and each axon can be supplied by several oligodendrocytes. Oligodendrocytes wrap the myelin around the axons in thin sheets like rolled up paper. Schwann cells, another kind of glial cell, makes a slightly different kind of myelin in the peripheral nervous system.When parts of the myelin sheath is lost, oligodendrocytes attempt to replace it. In acute MS lesions, typical of very aggressive disease courses, oligodendrocytes are found in large numbers and there is evidence of abortive remyelination-probably the new myelin is being destroyed faster than the oligodendrocytes can lay it down.