The central granule in many animal cells that appears to be the active principle of the centrosome and which undergoes duplication preceding the division of the centrosome proper.
A small structure found in the cytoplasm of a cell, which involved in forming the spindle during cell division.
A small particle found in the cytoplasm of cells, near the nucleus. Centrioles are involved in the formation of the spindle and aster during cell division. During interphase there are usually two centrioles in the centrosome; when cell division occurs these separate and move to opposite sides of the nucleus, and the spindle is formed between them.
A minute organelle consisting of a hollow cylinder closed at one end and open at the other, found in the cell center or attraction sphere of a cell. Before mitosis it divides, forming two daughter centrioles (diplosomes). During mitosis the centrioles migrate to opposite poles of the cell, and each forms the center of the aster to which the spindle fibers are attached.