The expression of ovulation related genes in CC is associated with patient and treatment characteristics, oocyte developmental potential and differs with the type of gonadotrophin used.

Multivariable models based on CC gene expression can be used to predict embryo development and pregnancy.

IVM of oocytes obtained ex vivo during the processing of ovarian cortex prior to cryopreservation is a procedure with emerging promise for patients at risk for fertility loss, as illustrated by the reported pregnancy. However, more data are needed in order to estimate the overall success rate and safety of this novel approach.

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STUDY QUESTION Can oocytes extracted from excised ovarian tissue and matured in vitro be a useful adjunct for urgent fertility preservation (FP)? SUMMARY ANSWER Ovarian tissue oocyte in-vitro maturation (OTO-IVM) in combination with ovarian tissue cryopreservation (OTC) is a valuable adjunct technique for FP. WHAT IS KNOWN ALREADY Despite the impressive progress in the field, options for FP for cancer patients are still limited and, depending on the technique, clinical outcome data are still scarce. STUDY DESIGN, SIZE, DURATION This was a retrospective cohort study conducted at a university hospital-affiliated fertility clinic between January 2012 and May 2019. PARTICIPANTS/MATERIALS, SETTING, METHODS The study included 77 patients who underwent unilateral oophorectomy for OTC. Cumulus-oocyte complexes (COCs) obtained during ovarian tissue processing were matured in vitro for 28–42 h. Oocytes reaching metaphase II stage were vitrified or inseminated for embryo vitrification. MAIN RESULTS AND THE ROLE OF CHANCE Overall, 1220 COCs were collected. The mean oocyte maturation rate was 39% ± 23% (SD). There were 64 patients who had vitrification of oocytes (6.7 ± 6.3 oocytes per patient). There were 13 patients who had ICSI of mature oocytes after IVM, with 2.0 ± 2.0 embryos vitrified per patient. Twelve patients have returned to the clinic with a desire for pregnancy. For seven of these, OTO-IVM material was thawed. Two patients had OTO-IVM oocytes warmed, with survival rates of 86% and 60%. After ICSI, six oocytes were fertilised in total, generating three good quality embryos for transfer, leading to a healthy live birth for one patient. In five patients, for whom a mean of 2.0 ± 0.8 (SD) embryos had been vitrified, seven embryos were warmed in total: one embryo did not survive the warming process; two tested genetically unsuitable for transfer; and four were transferred in separate cycles to three different patients, resulting in two healthy babies. In this small series, the live birth rate per patient after OTO-IVM, ICSI and embryo transfer was 43%. LIMITATIONS, REASONS FOR CAUTION The retrospective study design and the limited sample size should be considered when interpreting results. WIDER IMPLICATIONS OF THE FINDINGS The results of the study illustrate the added value of OTO-IVM in combination with OTC. We report the first live birth following the use of this appended technique combined with oocyte vitrification. STUDY FUNDING/COMPETING INTEREST(S) No external funding was used for this study. M.D.V. reports honoraria for lectures in the last 2 years from MSD and Ferring, outside the submitted work, as well as grant support from MSD. The other authors have nothing to declare. TRIAL REGISTRATION NUMBER N/A

Purpose Gene expression in human ART cumulus cell (CC) has been related to oocyte maturity and competence but requires further validation. Expression dynamics were investigated in CC of oocytes at different maturational stages and with different developmental competence in a standard in vivo mouse superovulation model. Methods Quantitative PCR analysis of Has2, Vcan, Sdc4, Alcam, Grem1, Ptgs1 and Ptgs2 in CC collected at regular time intervals from 0 to 24 h post hCG injection. Results Three expression patterns were observed each with strong regulation (4-230× differences). Immediately prior to ovulation CC of GVBD oocytes have 5× less Sdc4 and Ptgs1 and 5× more Ptgs2 when compared to the CC of freshly ovulated PB oocytes. When compared to the latter, the post-ovulatory aged PB oocytes had a 2× reduced blastocyst forming capacity and their CC expressed 2× more Sdc4 and 6× less Alcam. Conclusions Morphologically identical cumulus oocyte complexes with different developmental competence can be differentiated by CC gene expression.

Meiotic maturation of the oocyte is a timed sequence of events induced by the ovulatory LH surge. In vitro maturation of oocytes is known to alter the meiotic time course. This study documented the timing of meiosis in oocytes grown in vitro for 12 days, from the preantral follicle stage onward, and the influence of an oil overlay. In the oil-free culture, the stability of the metaphase II spindle was further explored to determine the postovulatory aging events. After the maturation stimulus, in vitro-grown oocytes were collected at 2-h intervals spanning the period of meiosis (0-18 h) and at 3-h intervals during early postovulatory aging (18-27 h). Stage of maturation was assessed both morphologically and by detailed spindle analysis and chromosome alignment. Results revealed that oil overlay did not impair the competence of cultured oocytes to proceed to meiosis II, but delayed meiosis I progression. Oil overlay during culture causes a different hormonal exposure of the follicles by a differential segregation into the oil overlay. The use of a progesterone receptor antagonist, however, did not induce a delay in meiotic progression. Aging effects in oil-free cultured follicles were detected 5 h after the establishment of the metaphase II spindle, comparable to their in vivo grown counterparts. The predominant effect of aging was an interphase-like appearance of the cytoskeleton. So an optimal time window for fertilization after in vitro follicular growth was determined to be 16-21 h after maturation induction.

Based on our experience, IVM is a valuable approach in patients with resistant ovary syndrome, but should not be recommended for patients with deficient oocyte maturation.