Physiological studies of sperm from normal and sub fertile men

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Men produce approximately 1000 sperm in every heartbeat. The main job of the sperm cell is to reach and fertilise the egg. However, we know very little about the journey the sperm makes in the female tract but we do know it must survive for up to 6 days and successfully navigate to the egg and 'drill' its entry path through the tough envelope that surrounds it. Success in this venture requires the deployment of strikingly different movement (motility) patterns which are controlled by the female reproductive tract through a series of finely tuned (but very poorly understood) stop/start signals. One key way the female tract communicates with the sperm is to manipulate the calcium level in a cell which then changes the way the cell moves. Surprisingly there are a large number of men (1:15) who produce sperm but their cells do not function in an optimal way. Such men have difficulties getting their partner pregnant. A primary cause of the sperm not working well is that they do not swim in the same manner as normal cells and a reason for this is that they have an abnormal calcium response to female reproductive tract signals. We do not know why these sperm have poor calcium responses. Very recently a specialised technique which allows us to obtain critical information on each sperm has been developed (patch clamping). This technique allows us to examine how calcium is changes in the sperm cell. We will use this specialised technique to study sperm from men with abnormalities and compare them to normal men. We anticipate that this will allow us to determine, for the first time, what are the specific problems in calcium regulation in sperm cells from men with fertility problems. If we can identify these problems it is possible that in the future we may be able to develop drugs to treat these abnormal cells and, conversely perhaps interrupt the calcium pathways in normal cells to develop a new male contraceptive.