Smooth Endoplasmic Reticulum Clusters in Oocytes From Patients Who Received Intracytoplasmic Sperm Injections Negatively Affect Blastocyst Quality and Speed of Blastocyst Development.

Xue Wang,Jingran Zhen,Qi Yu,Yaling Xiao,Zhengyi Sun

doi:10.3389/fphys.2021.732547

Abstract

Findings regarding the relationship between smooth endoplasmic reticulum clusters (SERCs) in oocytes and blastocyst development have been conflicting. In this study, the effects of SERCs on blastocyst quality and the speed of blastocyst development were evaluated. Patients who received intracytoplasmic sperm injections (ICSI) at our reproductive center from 2016 to 2020 were retrospectively analyzed. SERC (+) oocytes (n = 217) and SERC (–) oocytes (n = 822), as well as SERC (+) cycles (n = 146) and SERC (–) cycles (n = 1,951) were compared. There was no significant difference in embryological, clinical, and neonatal outcomes between the SERC (+) and SERC (–) cycles. The fertilization rate (73.9%), good quality blastocyst rate (26.7%) and the speed of blastocyst development (44.4%) were significantly lower (P < 0.05) in SERC (+) oocytes than in unaffected counterparts (86.2%, 44.1% and 63.4%, respectively). Furthermore, the proportion of blastocysts with trophectoderm (TE) grade C was significantly higher in the SERC (+) oocyte group than in the SERC (–) oocyte group (73.3 vs. 55.9%, P < 0.05). After adjusting for age, years of infertility, endometriosis, stimulation protocols (GnRHa), and male infertility, multiple logistic regression analysis revealed that the presence of SERCs in the oocytes significantly affected the speed of blastocyst development (odds ratio, 2.812; 95% CI, 1.257–6.292; P = 0.012). These findings suggest that the presence of SERCs in oocytes may negatively affect blastocyst quality and the speed of blastocyst development.

Highlights

Prolonging embryo culture in vitro to the blastocyst stage is conducive to the selection of viable embryos and thereby improves implantation rates (Glujovsky et al, 2016)
A total of 2097 intracytoplasmic sperm injections (ICSI) cycles were included, of which 146 cycles showed at least one oocyte with smooth endoplasmic reticulum clusters (SERCs)
After adjusting for age, years of infertility, endometriosis, stimulation protocols (GnRHa), and male infertility, multiple logistic regression analysis revealed that the presence of SERCs in the oocytes significantly affected the speed of blastocyst development (Table 4)

Summary

Introduction

Prolonging embryo culture in vitro to the blastocyst stage is conducive to the selection of viable embryos and thereby improves implantation rates (Glujovsky et al, 2016). Blastocysts cross the developmental block at the eight-cell stage of in vitro development At this stage, the synchronization of embryonic development and endometrial changes is more conducive to SERCs Negatively Affect Blastocyst Development blastocyst transfer (Shapiro et al, 2008), and the reduced contractile force of the uterine wall is conducive to implantation (Fanchin et al, 2001). When assisted reproductive technologies (ART) are used, some oocytes (obtained by controlled ovarian stimulation) might exhibit morphological abnormalities, including extracytoplasmic abnormalities, such as those in polar body morphology, perivitelline space, and zona pellucida, as well as cytoplasmic abnormalities, such as abnormal refractors, intracellular particles, vacuoles, and smooth endoplasmic reticulum clusters (SERCs) (ALPHA Scientists in Reproductive Medicine and ESHRE Special Interest Group Embryology, 2011)

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