目的 探究囊胚扩张过程中内细胞团和滋养外胚层间胞质丝的存在对胚胎发育和妊娠结局的影响。 方法 回顾性队列分析2019年6月至2021年12月于重庆市妇幼保健院生殖医学中心接受胚胎植入前遗传学检测（preimplantation genetic testing for aneuploidy，PGT-A），并行单囊胚移植治疗患者的临床资料。共纳入530例患者，2 132枚囊胚行PGT-A，按囊胚扩张过程中胞质丝的出现与否，将囊胚分为胞质丝（+）囊胚（n=534）和胞质丝（-）囊胚（n=1 598），比较2组囊胚的质量和PGT-A结果的差异，以及整倍体囊胚复苏移植后，胞质丝（+）（n=115）和胞质丝（-）囊胚（n=415）妊娠结局的差异。 结果 高质量组、一般质量组和低质量组囊胚的胞质丝（+）率分别为30.19%，24.62%和12.63%。胚胎质量与胞质丝（+）率的相关分析显示相关系数为-0.115（P<0.001）。2组囊胚的整倍体率（45.3% vs. 44.6%）差异无统计学意义。胞质丝（+）和胞质丝（-）的整倍体囊胚相比，种植率（72.17% vs. 66.02%，P=0.213）、流产率（14.46% vs. 12.77%，P=0.691）和活产率（61.74% vs. 57.59%，P=0.424）差异均无统计学意义。 结论 囊胚胞质丝的出现与囊胚形态学质量相关，与囊胚染色体倍性以及整倍体囊胚移植后的临床结局无关。

Objective To investigate the influence of inner cell mass and trophectoderm cytoplasmic strings during blastocyst expansion on embryonic development and pregnancy outcome. Methods A retrospective cohort analysis was performed for the clinical data of patients who received pre-implantation genetic testing for aneuploidy （PGT-A） and underwent single blastocyst transplantation in our hospital from June 2019 to December 2021. A total of 530 patients were enrolled，and genetic testing was performed for 2132 blastocysts. According to the presence or absence of cytoplasmic strings during blastocyst expansion，the blastocysts were divided into cytoplasmic strings（+） group with 534 blastocysts and cytoplasmic strings（-） group with 1598 blastocysts，and quality and PGT-A results were compared between the two groups. After the transfer of euploid blastocysts，pregnancy outcome was compared between the 115 blastocysts with cytoplasmic strings and the 415 blastocysts without cytoplasmic strings. Results The rates of cytoplasmic strings（+） in the high-，average-，and low-quality blastocyst groups were 30.19%，24.62%，and 12.63%，respectively. The correlation analysis showed a correlation coefficient of -0.115（P<0.001） between embryo quality and the rate of cytoplasmic strings（+）. There was no significant difference in euploidy rate between the two groups（45.3% vs. 44.6%）. There were no significant differences between the euploid blastocysts with cytoplasmic strings and those without cytoplasmic strings in implantation rate（72.17% vs. 66.02%，P=0.213），miscarriage rate（14.46% vs. 12.77%，P=0.691），and live birth rate（61.74% vs. 57.59%，P=0.424）. Conclusion The presence of cytoplasmic strings is associated with the morphological quality of blastocysts，while it has no impact on embryo ploidy or clinical outcome after euploid embryo transfer. Further research is needed to confirm the impact of cytoplasmic strings on embryonic development.