Correlation between Oocyte Morphology and Developmental Stages for Human Oocytes that Failed to Cleave after Intracytoplasmic Sperm Injection

Background: In the context of intracytoplasmic sperm injection (ICSI), oocyte maturity is estimated by the oocyte's appearance only, which may not reflect its actual maturity. Objectives: This study aims to compare the morphology of oocytes that failed to cleave after ICSI with the developmental status at which they were arrested. Methods: Human oocytes that failed to cleave after ICSI were collected from in vitro fertilization cycles. Oocytes were examined and photographed under a light microscope for morphological study, then immunostained to visualize the chromatin material (of the oocyte and the injected sperm) and the meiotic spindle. The morphologic features were compared with the oocyte developmental stage to identify any possible correlation. Results: 193 failed oocytes were collected, of which 182 were successfully immunostained and analyzed. Oocyte measurements did not differ significantly in relation to the developmental stage. Fine oocyte cytoplasmic granulation was connected with better oocyte maturity; dispersed granulation was connected with lower maturity levels, while central granulation was connected with the lowest oocyte maturity. A single polar body was significantly associated with early oocyte developmental stages, while two polar bodies were significantly associated with later developmental stages. Meiotic spindles were confined to metaphase-II oocytes. Oocyte morphology and measurements had no relation to the degree of sperm chromatin condensation. Conclusions: For the oocytes that fail ICSI, morphology correlates with the developmental stages. Fine cytoplasmic granulation is connected with better oocyte maturity, while dispersed and central granulation patterns are connected with lower maturity.