Cancer Research Campaign Growth Factors, Oxford University, United Kingdom.
The formation of germ cells, their progress through meiosis, and the earliest stages of development are times when the genes in normal organisms are in balanced conflict. One conflict is expressed as meiotic drive, a system which characteristically associated with low fertility. It is argued that the association between carcinoma in situ (CIS) and low fertility can be explained by assuming that some meiotic drive system is operating in the testis. In meiotic drive systems, single haploid sets of chromosomes are frequently prevented from contributing to the next generation. The progression of carcinoma in situ to the near triploidy of germ cell tumors is taken as supportive evidence that meiotic drive systems are operating during tumor formation. Another conflict system is the opposing interests of the genes inherited from each parent. In general, genes inherited from the father promote growth and those from the mother limit the growth of the normal conceptus. In germ cell tumors, it is not known if the chromosomes retain a memory of their parent.