Markers of growth and development in primate primordial follicles are preserved after slow cryopreservation

Objective: To investigate the effect of slow cryopreservation on the morphology and function of primate primordial follicles within ovarian tissue slices. Design: Fresh monkey ovarian tissue was frozen by slow cryopreservation and thawed for analysis of morphologic and functional parameters. Setting: University-affiliated laboratory. Animals: Rhesus monkey ovarian tissue. Intervention(s): None. Main Outcome Measure(s): Histologic analysis, follicle counting, assessment of protein abundance and localization. Result(s): After freezing and thawing, 89% of the primordial follicles maintained their laminar-based architecture, with sizes close to those of fresh fixed follicles. Molecular markers of early follicle health (activin subunits and the phosphorylated form of the signaling protein Smad2 [pSmad2]) were present in fresh and frozen-thawed primordial follicles. Stroma cells, but not follicles, had a higher level of TUNEL staining. Granulosa cells within the follicles of frozen-thawed ovarian tissue cultured for 48 hours had the capacity to proliferate and sustained expression of the activin subunits and nuclear pSmad2. Conclusion(s): This study provides evidence that markers of early follicle growth and development are preserved after slow cryopreservation and thaw, with little effect on follicle morphology and function.