The correct order of the steps of the formation sequence for a terrestrial planets are; A collapse, condensation, accretion, clearing Terrestrial planets are formed through the process called accretion. Accretion is when the microscopic solid particles that condensed grow into planets. The microscopic particles are able to stick together through electrostatic forces and not through gravitational attraction because these particles are too small.
Macrophages (histiocytes) - are phagocytes - these cells 'eat' particles such as bacteria. These cells are derived from white blood cells called monocytes (see the section on blood). :)
