Correlation between Cytoplamic Oocyte Maturation and Chromosomal Aneuploidies - Impact on fertilization, embryo quality and pregnancy

Abstract

Oocyte cytoplasmic immaturity is related to metaphase plate anomalies and aneuploidies. Fertilized oocytes, from a cohort with sub optimal fertilization with cytoplasmic immaturity, had poorer reproductive outcomes.

Euploidy rates in donor egg cycles significantly differ between fertility centers

“…Physicians may also follow different routines during follicle aspiration, for example which follicles they choose to aspirate and at what negative pressure, whether they tend to flush follicles or not, and differences in time between hCG administration and egg retrieval. Smaller follicles harbor more immature eggs, which have a higher incidence of chromosome abnormalities, and following IVM and IVF, these eggs lead to a higher incidence of multinucleation (De Vincentiis et al, 2013;Alvarez Sedo et al, 2015); multinucleation, in turn, has been associated with a high rate of chromosome abnormality (Kligman et al, 1996;Munné, 2006;Munné et al, 2007). Contaminants and volatile compounds could be also contributing to these differences in aneuploidy rates (Hunt et al, 2003, Susiarjo et al, 2007.…”

Pnma5 is essential to the progression of meiosis in mouse oocytes through a chain of phosphorylation

“…Secondly, Pnma5 knockdown dramatically increased abnormal MII oocytes with less congressed chromosomes. Since abnormal chromosome congression is an important form of cytoplasmic immaturation and has been thought to cause decreased fertilization rate [ 36 , 37 ], so probably it is one of the major factors causing abnormal fertilization in Pnma5-knockdown oocytes. And Pnma5 knockdown also dramatically disrupted mitochondrial distribution and significantly decreased ATP levels in maturated MII oocytes.…”

High proportion of immature oocytes in a cohort reduces fertilization, embryo development, pregnancy and live birth rates following ICSI

“…On the other hand, cytoplasmic maturation cannot be objectively determined and is often subtle (Balakier et al, 2004) and can only be inferred by the behaviour of cortical granules (Sathananthan et al, 2006). Targeted attempts have been able to link ooplasmic maturity to a reduction in a maturation promoting factor as visualized by pCdc2-Y15 antibodies (Alvarez Sedo et al, 2015). Cytoplasmic immaturity is also associated with sudden breakage of the plasma membrane during ICSI, resulting in an abnormal injection funnel (Palermo et al, 1995b).…”