01060nas a2200121   4500008003900000245013300039210006900172300000900241490001400250520060900264100001600873856004900889       2004                          d00aThe origin, ultrastructure and microbiology of the sediment accumulating in Dewars used for the storage of cryopreserved samples0 aorigin ultrastructure and microbiology of the sediment accumulat  aS1140 v82 Supl.23 aCONCLUSION: Ice crystals present in liquid nitrogen storage vessels concentrate biological contamination and provides a mechanism by which cryopreserved samples may become contaminated during storage. The association of the microbial contamination with ice may also provide ways to minimise the problem. A related issue is that storage vessels which have been maintained for several years would be expected to contain a high level of contamination which may be a risk to operators. This aspect has generally been overlooked and should be included in the development of safety policy for IVF laboratories.1 aMorris, G J  uhttps://www.notifylibrary.org/reference/1041