Dysmorphic patterns are associated with cytoskeletal alterations in human oocytes

Abstract
Study question: Are specific morphological anomalies in human mature oocytes, as revealed by transmitted light microscopy, associated with intrinsic damage to the meiotic spindle and actin cytoskeleton?
Summary answer: Aggregates of smooth endoplasmic reticulum (SER) and domains of centrally localized granular cytoplasm (GC) reflect intrinsic damage to the oocyte cytoskeleton, namely alterations in spindle size, chromosome misalignment and cortical actin disorganization.
Main results and the role of chance:In comparison with control oocytes, both SER and GC oocytes showed greater spindle length (P = 0.033 and 0.003, respectively) and GC oocytes also showed greater spindle width (P= 0.049) and area (P= 0.036). Control and SER oocytes had statistically comparable rates of chromosome displacement from the metaphase plate, unlike GC oocytes where chromosome displacement occurred at higher rate (P = 0.013). In situations where a complete Z-stack was reconstructed from a polar angle, chromosome disposition was classified as being normal when two sets of concentric arrays were visible. Based on these parameters, the proportions of oocytes with normal chromosomal arrangement or partial/total disarrangement was not statistically different between control and SER oocytes. Conversely, in GC oocytes, chromosome disarrangement was higher (P = 0.002). All control oocytes displayed a continuous meshwork of suboolemmal actin, which appeared as an uninterrupted ring in thin optical sections. In contrast, in SER and GC groups, integrity of suboolemmal actin was observed in only 66.7 and 42.9% of oocytes, respectively (P = 0.0001).

Autori: Mariabeatrice Dal Canto , Maria Cristina Guglielmo , Mario Mignini Renzini , Rubens Fadini , Clarissa Moutier , Maria Merola , Elena De Ponti, Giovanni Coticchio