Abstract: The disclosure relates to an ante-chamber for pre-sterilising components/materials to be supplied to a processing enclosure (e.g., an isolator enclosure, room, cabinet or the like) the ante-chamber having a closable entry for receipt of components/materials and a closable exit for supply of materials/components to the isolator enclosure, valve control and supply and return conduits for sterilant vapour for sterilizing the chamber and its contents and valve controlled supply and purge gas conduits for purging the chamber of sterilant at the end of the sterilizing operation. The supply and return conduits having filters to filter out particles from the air being delivered to the chamber and recovered from the chamber respectively. The valves for controlling the supply and return conduits are disposed between the filters and enclosure, the arrangement being such that the supply and return conduits for purge gas may be arranged to receive sterilant vapour periodically to sterilize the conduits.