Vitrification of testicular tissue from prepubertal cats in cryotubes using different cryoprotectant associations

Abstract

Protocols for the cryopreservation of testicular tissue are not yet established. In cats, few studies have been conducted on testicular vitrification using different cryoprotectant associations (CPAs). Thus, the objective of this study was to compare the effect of different CPAs on the vitrification of testicular tissue from prepubertal cats in cryotubes. We used 10 pairs of testicles, with each pair divided into 8 fragments that were distributed into different experimental groups. Two of these fragments were allocated into the control group (CG) and the other six were distributed according to the CPAs to be tested (dimethyl sulfoxide (DMSO)/glycerol (GLY), ethylene glycol (EG)/GLY, or DMSO/EG). The cryoprotectants were used at a final concentration of 5.6 M. The fragments were subjected to vitrification in cryotubes and after 1 week, they were warmed and processed for histomorphologic assessment, quantification of nucleolar organizer regions (NORs), and determination of cell viability. The DMSO/EG and EG/GLY groups presented the greatest cell separation from the cell basement membrane and the highest degrees of retraction of the basal membrane. In these aspects, DMSO/GLY did not differ from the CG and both were significantly superior to the other groups. In terms of cell distinction, visibility of the nucleus, and nuclear condensation, all the vitrified groups had significantly lower values than the CG, while the DMSO/GLY and EG/GLY groups did not differ between themselves. Through the quantification of NORs, the potential for cell proliferation of the CG was found to have a mean of 3.80, while DMSO/GLY presented a mean of 3.60, and thus there was no significant difference between these two groups. The proliferation potentials of both groups were significantly superior to that of the DMSO/EG (mean: 2.07) and EG/GLY (mean: 1.98) groups. In the CG and DMSO/GLY group, 91.8% and 64.2% of cells, respectively, were found to be viable. The cell viabilities of both groups were significantly superior to those of DMSO/EG (52.5%) and EG/GLY (57.10%). Vitrification in cryotubes combined with the use of the DMSO/GLY association was effective in maintaining the histomorphology, cell proliferation potential, and cell viability of testicular tissue from prepubertal cats after cryopreservation.