Cryopreservation of collared peccary ( Pecari tajacu L., 1758) epididymal sperm using extenders based on Tris and powdered coconut water (ACP®-116c)

Cryopreservation of Spix's yellow-toothed cavy epididymal sperm using Tris- and coconut water-based extenders supplemented with egg yolk or Aloe vera

Addressing the establishment of biobanks for the conservation of wild hystricomorph rodents' germplasm, we verified the effects of different extenders and distinct concentrations of non-permeant cryoprotectants on the sperm parameters of Spix's yellow-toothed cavies. Nine testis-epididymis complexes were used for sperm collection by retrograde washing using Tris or a powdered coconut water extender (ACP®-116c). Spermatozoa were diluted and frozen with the same extenders supplemented with egg yolk or Aloe vera at a 10% or 20% concentration. After recovery and cryopreservation, all samples were evaluated for sperm kinetic parameters, morphology, membrane integrity, osmotic response, and sperm-binding capability using an egg yolk perivitelline membrane assay. After recovery, no differences were observed between Tris and ACP®-116c that provided 515.4 × 10⁶ sperm/mL and 561.6 × 10⁶ sperm/mL, presenting >65% motile sperm, respectively. After cryopreservation, most effective preservation of sperm kinetic parameters (68.1 ± 5.9% motile sperm) and membrane integrity (48.2 ± 7.4%) was provided by Tris extender supplemented with 10% egg yolk. However, both extenders supplemented with any concentration of egg yolk or Aloe vera presented similar preservation of osmotic response and sperm-binding ability after cryopreservation. In summary, we suggest the use of a Tris extender supplemented of 10% egg yolk for cryopreservation of Spix's yellow-toothed cavy epidydimal sperm.

Influence of different extenders on morphological and functional parameters of frozen-thawed spermatozoa of jaguar (Panthera onca)

Due to the global decrease in jaguar population, conservation strategies are essential and the development of effective semen cryopreservation protocols would contribute to the formation of germplasm banks. Therefore, the objectives were to (1) evaluate the use of TRIS and ACP-117c extenders for jaguar semen freezing, (2) describe the ultrastructural changes in sperm after cryopreservation, and (3) evaluate the binding capacity of the thawed sperm. Eight ejaculates from five mature individuals were collected by electroejaculation, extended in TRIS or a coconut based-extender (ACP-117c), and frozen in liquid nitrogen. Samples were evaluated for sperm motility, vigor, membrane functionality, mitochondrial activity, morphology (using light microscopy, scanning electron microscopy - SEM and transmission electron microscopy - TEM), sperm kinetic parameters (by computerized analysis - CASA), and sperm binding capability using an egg yolk perivitelline membrane assay. Samples preserved in TRIS presented better post-thaw motility (46.0 ± 7.7%) and membrane functionality (60.5 ± 4.2%) and higher mitochondrial activity (21.5 ± 3.7%) than those preserved in ACP-117c (20.9 ± 5.4% motile sperm; 47.1 ± 2.5% functional membrane; 11.8 ± 1.7% mitochondrial activity). Regarding ultrastructural evaluations, SEM showed that both extenders were able to preserve the superficial membrane of the sperm, but TEM revealed the occurrence of nuclear electron lucent points, especially in samples extended in ACP-117c. Additionally, TRIS also provided a higher number of sperm bound to the perivitelline membrane (29.5 ± 3.3%) in comparison to samples diluted in ACP-117c (18.6 ± 1.5%). Overall, we suggest the use of a TRIS-based extender for cryopreservation of jaguar semen.

Effect of cryoprotectant type and concentration on the vitrification of collared peccary (Pecari tajacu) ovarian tissue

The aim of the present study was to establish a protocol for solid surface vitrification of peccary ovarian tissue by using different cryoprotectants. Ovarian pairs from five adult females were fragmented and two fragments (fresh control group) were immediately subjected to morphological evaluation using classical histology, transmission electron microscopy, and viability analysis using fluorescent probes. The remaining fragments (n = 18) were vitrified using a solid surface method with different concentrations (3 or 6 M) of ethylene glycol (EG), dimethyl sulfoxide (DMSO) or dimethyl formamide (DMF). After 2 weeks, samples were re-warmed and evaluated. A decrease in the percentage of morphologically normal preantral follicles (PFs) was verified for all the groups in comparison to the fresh control (92.0 ± 2.8%); however, if only the primordial follicles are considered, the most effective preservation (P < 0.05) was achieved with the use of EG at 3 M (74.2±7.3%) or DMSO at 6 M (75.0 ± 4.2%). Ultrastructural analysis indicated there were well-preserved PFs in all the groups evaluated, having well-defined membranes, a few vacuoles, and organelles that were uniformly distributed throughout the cytoplasm, mainly round and elongated mitochondria in close association with lipid droplets. Viability was preserved (P <  0.05) with the use of EG at 3 (97%) or 6 (97%) M, DMSO at 3 (100%), and DMF at 6 (97%) M. Solid surface vitrification, therefore, is an effective method for conservation of peccary female germplasm, especially with the use of EG at 3 M, which was highly effective for preservation of both the morphology and viability of PFs.