Inverted microscopy-based assessment reveals major maturation gap between denuded and non-denuded GV oocytes: A novel...

To compare the maturation rate and developmental potential of immature oocytes subjected to and spared from cumulus-oocyte complex (COC) denudation.

This single-center prospective observational study was conducted between 15 November-15-December 2025. Germinal vesicle (GV) oocytes were allocated to two groups: Group 1 included oocytesobtained from follicles >10 mm and identified as GV following denudation, whereas group 2 included immature oocytes retrieved from non-dominant follicles with diameter <10 mm, and assessed under an inverted microscope immediately after oocyte retrieval and placed into culture medium without being denuded. All immature oocytes were cultured separately in Continuous Single Culture-NX Complete medium, supplemented with gentamicin and human serum albumin, for 24 hours. COCs in group 2 were subsequently denuded and evaluated for nuclear maturation. Oocytes reaching metaphase II (MII) underwent intracytoplasmic sperm injection. The primary outcome was the MII maturation rate; secondary outcomes included 2PN formation rate and cleavage-stage embryo rate.

A total of 885 oocytes were retrieved from 52 patients. Group 1 included 84 denuded GV oocytes, and group 2 comprised 141 non-denuded COCs. After 24 hours of culture, maturation rates in groups 1 and 2 were 3/84 (2.37%) and 52/141 (36.9%), respectively. In group 1, only one oocyte was fertilized, and the resulting embryo arrested on day 3. In group 2, the fertilization and day-3 embryo rates were 23/48 (47.9%) and 14/23 (73.4%), respectively.

Non-denuded immature oocytes demonstrated significantly higher maturation, fertilization, and embryo development rates compared with denuded oocytes.