A simplified liquid nitrogen vapour method for the cryopreservation of human semen

A simple manually operated liquid nitrogen vapour freezing apparatus has been developed for the cryopreservation of human semen. A test method using this apparatus was evaluated by comparison with a conventional freezing method using an ultra cold (-70 degrees C) freezer. Twenty different unselected fresh semen samples were analysed, diluted with cryoprotective medium and then divided into equal numbers of straws prior to freezing by the two methods. A comparison of the average sperm motility before freezing and after thawing using these two methods demonstrated a statistically significant superiority of the simplified test method.