Rights: University of Waikato. All Rights Reserved. Micrographs courtesy of Tony Poole Published 29 February 2012 Size: 280 KB

The primary cilium (left) is a small organelle that acts like an antenna, co-ordinating information about the cell’s surroundings. The primary cilium is only just big enough to be viewed through an optical microscope (centre), but its structure can be studied in detail by using a transmission electron microscope (TEM)(right).