Effects of storing queen ovaries in saline solution at 22 C on ovarian follicle integrity and oocyte quality and maturation

This study evaluated the effects of storing queen ovaries in saline at 22 °C for up to 12 h. Two experiments were conducted. In the first experiment, ovaries from five queens were sectioned into four fragments; stored for 4, 8, or 12 h; and histologically analyzed to assess follicular morphology (Grades I-IV). In the second experiment, ovaries from 15 additional queens were stored under the same conditions, after which cumulus-oocyte complexes (COCs) were retrieved and graded (I-IV); only Grades I and II underwent in vitro maturation to assess cumulus expansion and meiotic status. The effects of storage on follicle morphology, COC quality, and maturation were analyzed using the chi-square test, while Spearman's correlation assessed the relationship between storage time and follicle morphology. The results showed that early-stage follicles were more sensitive to short-term storage, with 56 %, 22 %, 2 %, and 0 % of primordial, primary, secondary, and antral follicles, respectively, classified as Grade IV after 4 h. Grade I follicles declined to 0 % across all developmental stages after 12 h. Significant correlations were found between storage duration and follicle morphology (Grade I: r = -0.92, Grade II: r = -0.65, Grade III: r = 0.68; P < 0.05), while Grade IV remained unchanged. COC recovery did not differ across storage times (P > 0.05), with >60 % classified as Grade III or IV at all time points. After 12 h, there was a significant reduction in Grade I COCs, cumulus expansion, and the percentage of oocytes reaching metaphase II (P < 0.05). In conclusion, while storing queen ovaries in saline at 22 °C negatively affects follicular morphology - particularly preantral follicles - oocytes can still be recovered up to 8 h post-storage, without compromising COC quality or maturation potential.