Androgen receptors in the bonnethead shark, Sphyrna tiburo: CDNA cloning and tissue-specific expression in the male reproductive tract

•First major study on AR targets in male reproductive organs of a shark species.•AR mRNA and protein were detected in bonnethead testis and genital ducts.•Temporal changes in AR expression occur in association with the reproductive cycle.•Most AR targets in sharks are similar to those reported in higher vertebrates.•Unusually high AR mRNA expression occurs in mature spermatozoa.