In order to develop better methods for diagnosis and treatment of infertility, as well as safer contraceptives, more must be learned about how mammalian sperm move through the female reproductive tract. Crucial phases of mammalian sperm transport include passage through the cervix and uterotubal junction, storage of sperm in the oviductal storage reservoir, release from the reservoir, and location of the egg. There is some evidence for the existence of special passageways for sperm in the cervix, but this needs to be demonstrated and the mechanism of guiding sperm through the cervix needs to be elucidated. Passage of sperm through the uterotubal junction requires sperm to have certain proteins, but how these proteins function is not known. There is evidence that sperm must undergo motility hyperactivation in order to be released from the oviductal storage reservoir; however, the process is not understood. Finally, it is not clear whether there are chemotactic agents that emanate from the vicinity of the egg to modulate sperm flagellar beating patterns in order to guide them toward the egg. There are three main areas in which bioengineers can provide crucial help for elucidating these mysteries: (1) by developing a method for measuring and comparing sperm flagellar bending patterns, (2) by improving optical equipment for viewing the movement of sperm within the female reproductive tract, and (3) by developing chambers that mimic the physical environment of the tract so that molecular mechanisms that regulate sperm movement can be elucidated. USDA CSREES NRICGP 2008-35203-19031 and NIH 1RO3HD062471-01.