Freezing of testicular tissue as a minced suspension preserves sperm quality better than whole-biopsy freezing when glycerol is used as cryoprotectant

Frozen-thawed testicular spermatozoa have been used successfully for ICSI, especially in cases of obstructive azoospermia with normal spermatogenesis. Fewer attempts, however, have been made to check whether these rather imma ture spermatozoa, in a different environment with several other cell types present, have cryobiological requirements other than those of ejaculated sp ermatozoa. This is the reason why the freezing protocols and cryoprotectant s (glycerol) used for freezing testicular tissue are based on experience wi th semen freezing. This study aimed to assess whether cryosurvival and/or m otility was influenced by freezing of testicular tissue either as an intact biopsy or as a shredded tissue suspension, when glycerol was used as cryop rotectant. Freezing of testicular tissue as a suspension preserved motility (type B + C) significantly better than freezing of whole biopsies (9.2% vs . 4.0%). Similar observations have been made for vitality (39.3% vs. 25.4%) . Centrifugation on 50% Percoll in order to remove the cryoprotectant resul ted in a huge loss of spermatozoa (or late spermatids) and should therefore be especially avoided in cases of testicular failure. On the basis of thes e observations, mincing of the testicular biopsies before freezing may be a dvocated. Testicular spermatozoa seem to be better preserved when frozen in suspension, at least when slowly permeating glycerol is used as a cryoprot ectant.