title: Continuous assessment of human spermatozoa viability during cryopreservation.
abstract: Cryomicroscopy has enabled direct observation of freezing and thawing of human spermatozoa. When used with a fluorescent viability kit, sperm membrane damage was not apparent down to temperatures of -5 degrees C, but significant damage occurred after thawing (55% of spermatozoa had damaged membranes). Semen samples were cooled or frozen to temperatures (at decrements of 10 degrees C) from 0 degree C to -110 degrees C. At all these temperatures the proportion of live to membrane-damaged cells remained constant. Samples held at temperatures above -30 degrees C were not adversely affected. Below -30 degrees C there was a gradual increase in the proportion of membrane-damaged cells on thaw and a decrease in the number of live cells recovering motility. At temperatures between -50 degrees C and -60 degrees C there was an equal proportion of live motile, immotile, and membrane-damaged cells. It is concluded that some irreversible damage to spermatozoa was a result of freezing processes in cells frozen to -30 degrees C or less, but most of the cryodamage was incurred during thawing, possibly due to recrystallization.
authors.affiliation: University of Sheffield, Department of Obstetrics and Gynaecology, Jessop Hospital for Women, United Kingdom.
authors.forename: S N
authors.initials: SN
authors.lastname: Mohammad
authors.forename: C L
authors.initials: CL
authors.lastname: Barratt
authors.forename: I D
authors.initials: ID
authors.lastname: Cooke
authors.forename: H D
authors.initials: HD
authors.lastname: Moore
mesh_terms: D002470:Cell Survival / Q000502:physiology; D003080:Cold Temperature; D015925:Cryopreservation / Q000295:instrumentation / Q000592:standards*; D005456:Fluorescent Dyes; D006801:Humans; D008297:Male; D008856:Microscopy, Fluorescence; D012662:Semen Preservation / Q000295:instrumentation / Q000379:methods*; D013076:Sperm Count; D013081:Sperm Motility / Q000502:physiology
chemical_list: D005456:Fluorescent Dyes