Morphologic Features and Morphometric Measurements of Human Oocytes That Failed to Cleave after Intracytoplasmic Sperm Injection (ICSI)

Objective: Human oocytes collected for in vitro fertilization (IVF) vary in morphologic features and measurements. This study aimed to describe the morphology of human oocytes that failed to cleave after intracytoplasmic sperm injection (ICSI). Materials and Methods: Oocytes that failed to cleave post-ICSI were collected from IVF cycles. The oocytes were microscopically examined and the cytoplasmic diameter, zona pellucida thickness, perivitelline space (PVS) size, and first polar body (PBI) size were measured. The granularity pattern of cytoplasm; the color of cytoplasm; the presence of smooth endoplasmic reticulum (sER) aggregates, vacuoles, refractile bodies, and pronuclei; and, the status of polar bodies were all recorded. Results: A total of 142 oocytes were analyzed. The mean cytoplasmic diameter was 119.15±9.06 μm (range: 90.66-137.79 μm). The mean zona pellucida thickness was 19.29±3.69 μm (range: 12.86-33.69 μm). The mean PVS size was 3119.08 μm2 (range: 765-6448 μm2). The mean PBI size was 225.48±106.03 μm2 (range: 53.56-703.65 μm2). The cytoplasm showed fine (42.7%), dispersed (40.3%), central (14.5%), and uneven (2.54%) patterns of granulation. Other cytoplasmic abnormalities included refractile bodies (33.3%), sER aggregates (5.6%), vacuoles (5.6%), and dark cytoplasm (14.5%). A significant inverse correlation was found between the oocyte cytoplasmic diameter and PVS size. Conclusion: The morphologic abnormalities in oocytes that failed to cleave after ICSI are not significantly different from those observed in the general population of human oocytes. The oocyte cytoplasmic diameter was found to significantly inversely correlate with PVS size.