- Weitzel J, Shiryaeva N, Middendorff R, Balvers M, Radtke C, Ivell R, et al. Testis-specific expression of rat mitochondrial glycerol-3-phosphate dehydrogenase in haploid male germ cells. Biol Reprod. 2003;68:699-707 pubmed..Our results indicate that rat mGPDH is expressed by a testis-specific promoter from haploid male germ cells in a stage-specific manner. ..