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

Abstract

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.