A simplified technique for freezing human sperm for AIH: cryosyringe/floating platform of liquid nitrogen vapor.

A cryosyringe and floating platform were developed to simplify the procedures for human sperm cryopreservation without sacrificing post-thaw sperm quality. The cryosyringe was developed as a vessel for cryopreservation and as a device for post-thaw insemination. A platform-like polystyrene foam board 3-cm in height was floated on the surface of liquid nitrogen in a polystyrene foam freezing container. The cryosyringe containing sperm/KS-II medium mixture was placed on it for 5 min, then it was dropped into the liquid nitrogen. Freezing velocity was -27 degrees C/min. Poor quality semen specimens (40 +/- 14 x 10(6)/ml, 18 +/- 2.6% motility, n = 9) were concentrated (87 +/- 46 x 10(6)/nl, 29 +/- 9.1%) previously and then cryopreserved in the cryosyringe or in a commercial tuberculin syringe under the conditions established in the present study. The post-thaw sperm motility of the specimens in the cryosyringe (18 +/- 7.4%) was significantly superior (p less than 0.05) to that in the commercial tuberculin syringe (13 +/- 5.3% motility).