• Clinical and Experimental Reproductive Medicine
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• v.26 no.2
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• pp.251-256
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• 1999

The present study was conducted to evaluate whether vitrification could be used for ovarian tissue preservation. The important issue here is that the vitrification is very simple, easy, and economical compared to the conventional cryopreserving method that using automatic freezing instrument. Human ovarian cortical tissues were cryopreserved by vitrification with 5.5 M ethylene glycol and 1.0 M sucrose as cryoprotectant. Three points of temperature ($4^{\circ}C$, room temperature, and $37^{\circ}C$) and two points of duration (5 or 10 minutes) for cryoprotectant treatment were examined to determine the best condition for vitrification of the human ovarian cortical tissues. After thawing, viability of the isolated primordial follicles was examined by dye-exclusion method. Histological appearance of tissues before and after the cryopreservation was evaluated. There was no toxic effect of the 5.5 M ethylene glycol on the primordial follicles. However, when the tissues were treated with cryoprotectant at $37^{\circ}C$ for 10 minutes and exposed to liquid nitrogen, it seems likely that there is certain deleterious effects on the viability of the primordial follicles. The highest viability of the primordial follicles was obtained with the treatment of cryoprotectant at room temperature for 10 minutes. Follicles and oocytes survived after freezing and thawing had the similar normal shapes as was seen in the specimens before cryopreservation. It would be useful to apply vitrification in establishing ovarian tissue banking for clinical purposes.

• Clinical and Experimental Reproductive Medicine
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• v.27 no.2
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• pp.145-149
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• 2000

Objective: The present study was conducted to evaluate the viability of germ cells from the adult and fetal ovarian tissues after vitrification followed by xenografting. Method: The human adult ovarian tissues were obtained from 33 years old patient, and the fetal ovarian tissues were obtained from 22 weeks and 25 weeks in gestation. Ovarian tissues were cryopreserved by vitrification with 5.5 M ethylene glycol (EG 5.5) and 1.0 M sucrose as cryoprotectants. Adult and fetal ovarian tissues were pre-equilibrated with EG 5.5 at room temperature for 10 and 5 minutes, respectively and plunged into liquid nitrogen immediately. Frozen-thawed tissues were xenografted into NOD-SCID mice to evaluate the viability and capacity for further growth of the primordial follicles. Grafts were recovered from the recipients 4 weeks after transplantation and histological analysis was accomplished. Result and Conclusion: Grafts recovered 4 weeks after transplantation contained less number of oocytes and primordial follicles compared to that of the fresh tissues. Survived follicles were mainly primordial and intermediary with larger diameter and more granulosa cells. It is confirmed that 1) the ovarian tissues were healthy and the germ cells were survived after vitrification, and 2) the survived fetal primordial follicles after vitrification resumed the growth in the xenografts.