Dr. Yigal Gat, an expert in the field of male fertility, was invited to speak at a medical conference scheduled to take place in Teheran. "I intended to begin the presentation by explaining that a sperm cell is like a nuclear missile. It has six engines and it's aimed at a target," Gat told Army Radio. "The testicles are the factory that create the nuclear warheads. I'm sure that would have been very convincing for them." However, the Iranian organizers later notified Gat that he would not be permitted to attend the conference because he is an Israeli.