1 There are two types of glial cells in the nervous system: the large-bodied macroglia and the smaller microglia. 2  There are two classes of macroglia in the central nervous system: astrocytes and oligodendrocytes.
Exports directly contribute and imports directly reduce their nation's balance of trade (i.e. net exports). A trade surplus is positive net balance of trade, and a trade deficit is a negative net balance of trade.
DEFINITION of 'Trade Trigger'. Any type of event that triggers a securities trade. A trade trigger is usually a market condition, such as a rise or fall in the price of an index or security. Trade triggers are used to automate certain types of trades, such as selling shares of a stock when the price reaches a certain level. Next Up.