Objective:The aim of our study was to observe the survival and morphological changes of thawed ovarian tissues after heterotopic transplantation.Methods:Twenty SPF-SD female rats(5–6 weeks old) were equally randomized into the control group and experimental group.In control group,the freshly isolated ovaries were fixed in formalin.In experimental group,the freshly isolated ovaries were vitrified immediately and cut into thin slices.After stored in liquid nitrogen for 21 days,the tissues of experimental group were rapidly thawed and transplanted into back muscles of rats for 2 or 4 weeks,respectively.After that,all rats in experimental group were sacrificed and the ovarian tissues were collected and fixed in 4% formaldehyde solution.Then the ovarian tissues were stained with HE and observed under the light confocal microscope.Results:With the naked eyes,there was no specific alteration except the size reduction with color changing.Under microscopy,we found normal cortex and medulla in the ovary,and the primordial follicles and follicles in various stages were observed in the cortex.The normal oocytes in ovarian tissues of experimental group were significant decreased than in the control group.Conclusion:The ovarian tissues survive well in experimental group and there is no significant difference in the proportion of follicles between different times(2 and 4 weeks) after grafting.Our results suggest that thawed ovarian tissues could survive after heterotopic transplantation into back muscles of rat models and maintain their morphology and function. Objective: The aim of our study was to observe the survival and morphological changes of thawed ovarian tissues after heterotopic transplantation. Methods: Twenty SPF-SD female rats (5-6 weeks old) were equally randomized into the control group and experimental group. control group, the freshly isolated ovaries were fixed in formalin. In experimental group, the freshly isolated ovaries were vitrified immediately and cut into thin slices. After the fluid in liquid nitrogen for 21 days, the tissues of experimental group were rapidly thawed and transplanted into back muscles of rats for 2 or 4 weeks, respectively. After that, all rats in experimental group were sacrificed and the ovarian tissues were collected and fixed in 4% formaldehyde solution.Then the ovarian tissues were stained with HE and observed under the light confocal microscope .Results: With the naked eyes, there was no specific alteration except the size reduction with color changing .Under microscopy, we found normal cortex and medulla in the ovary, and the primordial follicles and follicles in various stages were observed in the cortex.The normal oocytes in ovarian tissues of experimental group were significantly decreased than in the control group. Confc: The ovarian tissues survive well in experimental group and there is no significant difference in the proportion of follicles between different times (2 and 4 weeks) after grafting.Our results suggest that thawed ovarian tissues could survive after heterotopic transplantation into back muscles of rat models and maintain their morphology and function.