Oocyte morphology does not correlate with fertilization rate and embryo quality after intracytoplasmic sperm injection

Abstract

The fertilization rates and further development of 528 human metaphase II oocytes directly injected by a single spermatozoon were analysed with respect to their morphological features at the light microscopy level at the time of retrieval. The deviations of oocyte morphology which were most frequently observed, after removal of cumulus cells, were dark incorporations, dark zona pellucida, large perivitelline space, spots, vacuoles, refractile bodies and irregular shape. These deviations correlated neither with the fertilization rate nor with the embryo quality score, as compared to 'ideal' oocytes. Since the majority of oocytes displayed deviations from the 'ideal' morphotype but were still fertilized and developed in culture at a normal rate, they were probably as normal as 'ideal' oocytes. Since some of these morphotypes, such as refractile bodies, have been shown to be associated with failure of fertilization, it seems that intracytoplasmic sperm injection may be an appropriate method of treatment for couples in whom repeated failure of in-vitro fertilization is associated with the retrieval of dysmorphic oocytes in the presence of normal semen characteristics.

The predictive value of high-magnification sperm morphology examination on ICSI outcomes in the presence of oocyte dysmorphisms

“…Nevertheless, more than half of all collected oocytes show at least one morphological abnormality [19,21].…”

An oocyte score for use in assisted reproduction

“…Human metaphase II oocytes have distinct morphological characteristics that may be indicative of quality and therefore used to predict implantation potential [21,[36][37][38][39][40][41][42][43]. For example, regular patterns of granularity have been observed in the oocyte cytoplasm and it has been suggested that these patterns correlate with oocyte quality [44,45].…”

“…Many other parameters have also been analysed in oocytes such as zona pellucida thickness, spindle birefringence and extracellular dysmorphisms [36,47,48]. Results vary as to whether distinct oocyte dysmorphisms have any relation to fertilisation and development rates, probably due to a discordance in the scoring of these dysmorphisms [50], although an effect on pregnancies is often noted [21,36,47,50].…”

Impact of oocyte morphological components on fertilization

“…Çalışmadaki olguların ortalama yaş, vücut kitle indeksi, antral folikül sayısı, matür oosit sayısı ve stimülasyon süresi sı-rasıyla 31.5±4. 2 …”

“…Oosit kalitesi polar cisimcik (PB), zona pellusida (ZP), perivitellin aralık ve oosit sitoplazma (OS) morfolojik özel-liklerine göre belirlenebilir diyenler olduğu gibi buna karşı çıkanlar da bulunmaktadır. [2,3] Yapılan çalışmala-rın bazıları oosit morfolojisinin fertilizasyon üzerine etkisi olmadığını, [4,5] bazıları da morfolojik özelliklerin fertilizasyonu ve embriyoner gelişimi etkilediğini bildirmektedir. [6,7] Morfolojik açıdan bakıldığında sitoplazmik granül, fragmanlı PB ve sitoplazmik vakuol varlığı oosit kalitesini bozmaktadır.…”