[Fertilizing capacity of fresh and frozen spermatozoa]

Although frozen semen is now being used clinically, the fertilizing function of thawed semen has not yet been evaluated adequately. The changes in frozen sperm functions were evaluated and the changes in regard to the fertilization phenomenon were also investigated. The collected semen was evaluated by the following function tests, 1) Bovine cervical Mucus Penetration test (BMP test), 2) Zona-free hamster egg Sperm Penetration Test (ZSPT), 3) Hypoosmotic Swelling test (HOS test), 4) Triple stain technique (AR test), 5) Semen Auto Analyzer. The freezing medium was KS-II solution with a program freezer (CRYO-10). The results were as follows: 1) In the BMP test, the frozen normospermic group maintained fertilizing capacity. 2) There was no significant difference between fresh and frozen semen in the penetration rate of ZSPT except in the oligospermic group. 3) In the HOS test, there was no difference between fresh and frozen specimens in the number of swollen sperms which endured freezing and maintained the sperm membrane integrity. 4) There was a tendency to compare to that of fresh semen the increase in AR in frozen semen, but it was not significant. 5) There were low values after thawing except for LHD, but there still remained fertilizability after freezing. In conclusion, there was no reduction in fertilizing capacity following freezing through out the sperm function tests.