Quantitation of sperm population migration: capillary scanning assay

Bulk sperm migration through capillaries containing experimental media was quantitated by use of a recording spectrophotometer equipped with a linear transport. The method was applied to human semen and caudal epididymal sperm samples from hamster, rat, rabbit, and bull. The rate of migration of a given sperm population was approximately 1/10 that of the velocities previously reported for individual sperm of that species. This matched theoretical approximations based upon assumptions of random orientation and multiple, direction-changing collisions for individual cells. The rate of migration for undiluted caudal epididymal sperm populations into Tyrode's solution for all species tested showed an initial burst followed by a slower, more linear rate. Predilution or prewashing the sperm samples eliminated the initial burst in hamster and rabbit sperm but elevated migratory rates in bull sperm. Human sperm populations diluted by ejaculation also exhibited no initial burst but maintained a strong linear rate down the capillaries.