Nuclear receptors are important regulators of development and reproduction whose action can be modulated by transcriptional intermediary factors (TIFs). In situ hybridization was used to investigate the expression pattern of the putative nuclear receptor mediator TIF1alpha during mouse embryogenesis and adult life. TIF1alpha is ubiquitously expressed until midgestation. At 12.5 gestational days, TIF1alpha is preferentially expressed in the developing central and peripheral nervous system. Differential expression persists until perinatal stages, with high expression in the brain, nasal epithelium and within proliferating regions of the kidney and teeth. In the adult, TIF1alpha expression is predominant in both the male and female gonads. Immunogold electron microscopy revealed that TIF1alpha protein is most abundant in the nuclei of male germ cells at various stages of their maturation.