Cryopreservation of human semen: comparison between methods of freezing and types of storage - Revista Brasileira de Ginecologia e Obstetrícia

PURPOSE: to compare two different methods of freezing and two types of human semen storage during cryopreservation process. METHODS: experimental research in which the cryopreservation of 18 semen samples from 18 volunteers was studied. Following the addition of the cryoprotectant medium, Test-yolk buffer, the semen samples were packaged into 0.25 mL straws or into 2 mL cryotubes and submitted to cryopreservation by slow or rapid methods, in four different treatments: RS (cryopreservation by rapid method and packaged in straws), RT (rapid-cryotubes), SS (slow-straws), and ST (slow-cryotubes). Samples were thawed after 24 hand then maintained at 37ºC. Data collected were analyzed by the Student t-test, with p<0.05, using the SPSS computer program for Windows®, version 11.0.0. RESULTS: the motility of spermatozoa decreased after the cryopreservation process. The initial motility rate was 58.1% and motilities after the different methods of cryopreservation were 19.2% (RS), 27% (RT), 21.1% (SS) and 30.3% (ST). There was a significant decrease of the normal morphology. The initial normal morphology was 14.2% and morphologies after the different methods of cryopreservation were 12.8% (RS), 12.6% (RT), 12.6% (SS) and 12.4% (ST). CONCLUSIONS: the slow method of cryopreservation with storage in cryotubes showed the best recovery of motile cells after freezing and thawing. There was no difference among the methods when appraised the morphology.