Genetic analysis of mammalian spermatogenesis: use of the t complex in the mouse in studies of spermatogenesis and sperm function.

Our observations suggest that sperm populations from the caudae epididymides of tw32/+ mice undergo hyperactivation in vitro sooner and to a much greater extent than do sperm populations from congenic +/+ mice: (1) epididymal tw32/+ sperm populations become significantly less progressive in vitro than do +/+ sperm populations; (2) low (0.1 mM) levels of Ca2+ prevent this loss of progressiveness; (3) epididymal tw32/+ sperm populations have trajectories and progressiveness values similar to both +/+ and tw32/+ oviductal sperm populations; (4) an inhibitor of capacitation inhibits the loss of progressiveness. This divergence from normal motility may be the result of expression of one of the factors involved in transmission distortion of the t complex.