The coxsackievirus and adenovirus receptor (CAR) is a cell adhesion molecule expressed in epithelial tight junctions and other cell-cell contacts. Using indirect immunofluorescence, qRT-PCR and Western blots the expression and distribution of CAR in developing and adult testis is examined. CAR is highly expressed in both Sertoli cells and germ cells during peri- and postnatal development, followed by a rapid downregulation of both mRNA and protein levels. Interestingly, we find that CAR is a previously unknown downstream target for follicle-stimulating hormone (FSH) since CAR mRNA levels were induced in primary cultures of FSH-stimulated Sertoli cells. In contrast to other epithelia, CAR is not a general component of tight junctions in the seminiferous epithelium, and Sertoli cells in the adult testis do not express CAR. Instead, CAR expression is stage-dependent and specifically found in migratory germ cells. RT-PCR also demonstrated the presence of JAML in the testis. JAM-L was previously reported by others to form a functional complex with CAR regulating transepithelial migration of leukocytes. The expression of JAML in the testis suggests that a similar functional complex might be present during germ cell migration across the blood-testis barrier. Finally, an intermediate compartment occupied by CAR-positive, migrating germ cells and flanked by two occludin-containing junctions is identified. Together these results implicate a function for CAR in testis morphogenesis and in migration of germ cells across the blood-testis barrier during spermatogenesis.