Vitrification of Feline Ovarian Tissue on Copper Grid Versus Acupuncture Needle Using Different Rates of Vitrification Solution

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Abstract

Objective: Ovarian tissue vitrification has been utilized in human and veterinary medicine. This study aims to compare two different carrier devices and three different compositions of cryoprotective agent (CPA) solutions in the feline ovarian tissue vitrification using either copper grids (CG) or acupuncture needles.

Methods: The fragments were divided into four groups as control, CG, needle immersed vitrification (NIV)-I and -II. For CG method, the final CPA concentration of the vitrification solution was 20% DMSO, 20% EG and 0.4 M sucrose. The final concentration of vitrification solution in NIV-I group consisted of 15% Dimethyl sulfoxide (DMSO), 15% Ethylene glycol (EG) and 0.5 M sucrose, where in NIV-II group 12% DMSO, 12% EG and 0.5 M sucrose. After equilibration in increasing graded CPAs, tissues were plunged into liquid nitrogen and stored for one week.

Results: The rate of normal follicles in NIV-I group was statistically higher than CG and NIV-II groups. Oocyte and follicle cells’ nuclei were intact in normal follicles in control group. Many normal oocytes and follicle cells were seen in vitrified groups, but the number of degenerated oocytes and follicle cells increased. The cell linkages between oocytes and follicle cells were preserved better in the NIV-I group than in the other experimental groups.

Conclusion: It was concluded that NIV-I technique (15% DMSO/EG and 0.5 M sucrose) was more efficient than other two techniques and favourable in preventing follicular damage on cryopreservation of ovarian tissue.