Messenger RNAs for several components of the transcriptional apparatus are greatly overexpressed in postmeiotic male germ cells in rodents (Schmidt and Schibler, Development 1995; 121:2373-2383). Because of the tight coupling of polyadenylation and transcription, we examined expression in germ cells of mRNAs for key polyadenylation factors. The mRNA for the 64 000 M(r) subunit of the cleavage stimulation factor (CstF-64) was expressed at least 250-fold greater in mouse testicular RNA than in liver RNA. RNA blot analysis showed that the mRNA for the 160 000 M(r) subunit of the cleavage and polyadenylation specificity factor was similarly overexpressed, as was the mRNA for the large subunit of RNA polymerase II. General transcription factors, such as the TATA-binding protein and transcription factor IIH, and splicing factors, such as components of the small nuclear ribonucleoproteins, were also expressed in meiotic and postmeiotic germ cells. The X-linked CstF-64 protein is expressed before and after but not during meiosis in the mouse (Wallace et al., Proc Natl Acad Sci U S A 1999; 96:6763-6768), which suggests that overexpression of mRNA transcription and processing factors plays an essential role in postmeiotic germ cell mRNA metabolism.