Expression of proto-oncogenes and protein kinases in the testis

Specificity of expression is regarded as a strong indication that genes play a role in determining the phenotype or function of the cells in which they are expressed. A molecular genetic approach to understanding the control of male germ cell differentiation involves, in part, identifying genes that are expressed in a spermatogenic cell type-specific manner. Previous observations from our laboratory and others have shown that some testis-specific genes are expressed in spermatogenic cells in a stage-specific manner. Similarly, more ubiquitously expressed genes can exhibit particularly abundant expression in germ cells, often of uniquely sized transcripts. Both patterns of expression suggest a role for these genes in spermatogenesis or subsequent function of male gametes (rev. in Willison and Ashworth 1987; Hecht 1990; Erickson 1990; Wolgemuth and Watrin 1991).