Improvement in the quality and fertilization potential of a human sperm population using the rise technique.

Semen from 63 individuals participating in an in vitro fertilization program was processed using a modified rise technique. Overall normal morphology was significantly improved in the rise (79.2%) as compared with the unprocessed sample (57.8%), and six of seven specific morphologic abnormalities were significantly reduced. Motility was significantly enhanced from 51.8% in the unprocessed samples to 89.1% in the rise samples. Spermatozoa recovered in the rise portion of the sample represented 5.9% of the total sample. Ultrastructural morphometry revealed that the rise was relatively free of abnormal sperm forms, acellular debris and non-sperm cellular elements as compared with the non-rise portion of the sample or a typical unprocessed sample. Volume density measurements demonstrated that only 18.1% of the volume of the non-rise sample was composed of normal spermatozoa compared with 83.4% of the volume of the rise. In a separate set of experiments utilizing 21 samples, the penetration of hamster eggs was significantly enhanced from 37.9% to 67.2% using spermatozoa from the initial washed sample and those from the rise, respectively. These data demonstrate the qualitative and quantitative improvements, as well as the increase in fertilizing potential, of the rise portion of the semen sample.