title: Appropriate Osmotic Balance Duration for Different Volumes of Ovarian Tissue in Vitrification Solution: a Study of Ovary Tissue Vitrification and Transplantation in Sheep.
abstract: BACKGROUND: Auto-transplantation of cryopreserved ovarian tissue has become a promising method for fertility preservation and standardization of the process is crucial for practical applications.
  
  
  
  Here we used different size of large sheep ovarian cortex to study the most suitable osmotic balance durations in the vitrification solution for large piece ovary cortex.
  
  
  
  The ovarian cortices from six-month old female sheep were divided into 40 cubic mm, 80 cubic mm and 160 cubic mm volume, A two-step osmotic balance method was used based on the results from morphological and histological study, we detected the expression of VEGF after thawing, the percentage of follicles that survived and serum E2 levels,together with apoptosis test by TUNEL.
  
  
  
  the morphology of follicles and stromal cells were the best when the osmotic balance duration was 7 min, 11 min and 19 min, respectively. Osmotic balance time(T) is proportional to the area(S), we deduced that areas(S) of large pieces of ovarian cortex in vitrification fluid conformed to the standardized osmotic balance time(T) formula; i.e., T=（S+15)/5 (22~24C, sample thickness 1-2 mm), In vitro culture of vitrification-thawed large cortex ovaries and xenogenic heterotopic transplantation by using the standardized osmotic balance duration formula were both successful.
  
  
  
  Formula T=（S+15)/5 can be used to calculate optimal osmotic balance duration for different size of ovarian cortexes during vitrification.
authors.affiliation: Key Laboratory of Fertility Preservation and Maintenance, Ministry of Education, Key Laboratory of Reproduction and Genetics in Ningxia, Department of Histology and Embryology, Nursing school, Ningxia Medical University, Ningxia, 75004, P.R. China.
authors.forename: L
authors.initials: L
authors.lastname: Dang
authors.affiliation: Key Laboratory of Fertility Preservation and Maintenance, Ministry of Education, Key Laboratory of Reproduction and Genetics in Ningxia, Department of Histology and Embryology, Nursing school, Ningxia Medical University, Ningxia, 75004, P.R. China.
authors.forename: X
authors.initials: X
authors.lastname: Zheng
authors.affiliation: Key Laboratory of Fertility Preservation and Maintenance, Ministry of Education, Key Laboratory of Reproduction and Genetics in Ningxia, Department of Histology and Embryology, Nursing school, Ningxia Medical University, Ningxia, 75004, P.R. China.
authors.forename: Q
authors.initials: Q
authors.lastname: Chang
authors.affiliation: Key Laboratory of Fertility Preservation and Maintenance, Ministry of Education, Key Laboratory of Reproduction and Genetics in Ningxia, Department of Histology and Embryology, Nursing school, Ningxia Medical University, Ningxia, 75004, P.R. China.
authors.forename: Y
authors.initials: Y
authors.lastname: Yang
authors.affiliation: Department of Histology and Embryology, XingTai Medical College, Ningxia, 75004, P.R. China.
authors.forename: Y
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Key Laboratory of Fertility Preservation and Maintenance, Ministry of Education, Key Laboratory of Reproduction and Genetics in Ningxia, Department of Histology and Embryology, Nursing school, Ningxia Medical University, Ningxia, 75004, P.R. China.
authors.forename: Y
authors.initials: Y
authors.lastname: Cai
authors.affiliation: Key Laboratory of Fertility Preservation and Maintenance, Ministry of Education, Key Laboratory of Reproduction and Genetics in Ningxia, Department of Histology and Embryology, Nursing school, Ningxia Medical University, Ningxia, 75004, P.R. China.
authors.forename: C
authors.initials: C
authors.lastname: Hei
authors.affiliation: Key Laboratory of Fertility Preservation and Maintenance, Ministry of Education, Key Laboratory of Reproduction and Genetics in Ningxia, Department of Histology and Embryology, Nursing school, Ningxia Medical University, Ningxia, 75004, P.R. China.
authors.forename: H
authors.initials: H
authors.lastname: Wang
authors.affiliation: Key Laboratory of Fertility Preservation and Maintenance, Ministry of Education, Key Laboratory of Reproduction and Genetics in Ningxia, Department of Histology and Embryology, Nursing school, Ningxia Medical University, Ningxia, 75004, P.R. China.
authors.forename: C
authors.initials: C
authors.lastname: Zhao
authors.affiliation: Key Laboratory of Fertility Preservation and Maintenance, Ministry of Education, Key Laboratory of Reproduction and Genetics in Ningxia, Department of Histology and Embryology, Nursing school, Ningxia Medical University, Ningxia, 75004, P.R. China.
authors.forename: W
authors.initials: W
authors.lastname: Zhu
authors.affiliation: Key Laboratory of Fertility Preservation and Maintenance, Ministry of Education, Key Laboratory of Reproduction and Genetics in Ningxia, Department of Histology and Embryology, Nursing school, Ningxia Medical University, Ningxia, 75004, P.R. China.
authors.forename: Y
authors.initials: Y
authors.lastname: Wang
mesh_terms: D000818:Animals; D017209:Apoptosis; D015925:Cryopreservation; D003451:Cryoprotective Agents / Q000737:chemistry*; D005260:Female; D059247:Fertility Preservation / Q000379:methods; D009995:Osmosis; D010053:Ovary / Q000166:cytology* / Q000637:transplantation*; D012756:Sheep; D016042:Transplantation, Heterotopic; D058989:Vitrification
chemical_list: D003451:Cryoprotective Agents