Abstract
BackgroundThis study evaluated whether there is a relationship between the zona pellucida birefringence (ZP-BF) intensity and the nuclear (NM) and cytoplasmic (CM) in vitro maturation of human oocytes from stimulated cycles.ResultsThe ZP-BF was evaluated under an inverted microscope with a polarizing optical system and was scored as high/positive (when the ZP image presented a uniform and intense birefringence) or low/negative (when the image presented moderate and heterogeneous birefringence). CM was analyzed by evaluating the distribution of cortical granules (CGs) throughout the ooplasm by immunofluorescence staining. CM was classified as: complete, when CG was localized in the periphery; incomplete, when oocytes presented a cluster of CGs in the center; or in transition, when oocytes had both in clusters throughout cytoplasm and distributed in a layer in the cytoplasm periphery Nuclear maturation: From a total of 83 germinal vesicle (GV) stage oocytes, 58 of oocytes (69.9%) reached NM at the metaphase II stage. From these 58 oocytes matured in vitro, the high/positively scoring ZP-BF was presented in 82.7% of oocytes at the GV stage, in 75.8% of oocytes when at the metaphase I, and in 82.7% when oocytes reached MII. No relationship was observed between NM and ZP-BF positive/negative scores (P = 0.55). These variables had a low Pearson's correlation coefficient (r = 0.081). Cytoplasmic maturation: A total of 85 in vitro-matured MII oocytes were fixed for CM evaluation. Forty-nine oocytes of them (57.6%) showed the complete CM, 30 (61.2%) presented a high/positively scoring ZP-BF and 19 (38.8%) had a low/negatively scoring ZP-BF. From 36 oocytes (42.3%) with incomplete CM, 18 (50%) presented a high/positively scoring ZPBF and 18 (50%) had a low/negatively scoring ZP-BF. No relationship was observed between CM and ZP-BF positive/negative scores (P = 0.42). These variables had a low Pearson's correlation coefficient (r = 0.11).ConclusionsThe current study demonstrated an absence of relationship between ZP-BF high/positive or low/negative score and nuclear and cytoplasmic in vitro maturation of oocytes from stimulation cycles.
Highlights
This study evaluated whether there is a relationship between the zona pellucida birefringence (ZP-BF) intensity and the nuclear (NM) and cytoplasmic (CM) in vitro maturation of human oocytes from stimulated cycles
Oocyte retrieval was performed after 36 hours of rhCG administration by transvaginal ultrasound-guided aspiration. Participants This prospective study was conducted on 92 patients who were admitted to an intracytoplasmic sperm injection (ICSI) program at the Center for Human Reproduction Prof
Nuclear maturation From a total of 83 germinal vesicle (GV) oocytes, 58 oocytes (69.9%) reached nuclear maturation (NM) (MII stage). From these 58 oocytes matured in vitro, a high/positively scoring ZP birefringence (ZP-BF) was presented in 82.7% of GV oocytes, 75.8% of MI oocytes, and 82.7% of MII oocytes
Summary
This study evaluated whether there is a relationship between the zona pellucida birefringence (ZP-BF) intensity and the nuclear (NM) and cytoplasmic (CM) in vitro maturation of human oocytes from stimulated cycles. When the oocyte is preparing for ovulation and interaction with spermatozoon, a series of changes occur inside of this cell. This is a complex process that includes nuclear, meiotic and cytoplasmic events [1]. To reach optimal competence for further development, cytoplasmic oocyte maturation (CM) must occur in synchronization to nuclear maturation (NM). The zona pellucida (ZP) is a unique extracellular coat that surrounds the maturing oocyte during ovulation, fertilization and early embryonic development [2]. According to Montag et al [5], a high/positively scoring ZP-BF probably reflects a healthy oocyte with full nuclear and cytoplasmic maturation
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have