Abstract
Fertility, pre-freeze and post-thaw sperm motility, penetration ability and duration of motility in cervical mucus of spermatozoa were studied in 7 heterologous insemination donors and in 4 men in connection with homologous inseminations. No conception occurred after 50 heterologous and 15 homologous inseminations using semen preserved at—196d`C. The post-thaw motility, penetration ability and duration of motility in cervical mucus of spermatozoa were reduced by the freeze-preservation procedure. The fertilizing capacity of freeze-pre-served semen was more reduced than expected from the post-thaw sperm motility and penetration ability. The semen quality was of significant importance for the post-thaw sperm motility and penetration ability.