Abstract
BACKGROUND: cDNA libraries derived from the brain and testis contain genes that encode almost all proteins. The brain is composed of various differentiated cells, and the testis also contains various differentiated cells, such as germ cells, and somatic cells that support germ cell differentiation, such as Sertoli and Leydig cells. Many genes appear to be expressed due to tissue complexity. METHODS: The Genome Project has sequenced the entire genomes of humans and mice. Recent research using new gene analysis technologies has found that many genes are expressed specifically in male germ cells. MAIN FINDINGS RESULTS: Functional intronless genes are significantly enriched in haploid germ cell-specific genes. CONCLUSION: Functional intronless genes associated with fertility are more likely to be inherited in haploid germ cells than in somatic cells.