Importance of cytoplasmic granularity of human oocytes in in vitro fertilization treatments.

The aim of this study was to examine the effect of different stimulation protocols on oocyte granularity and to determine the influence of cytoplasmic granularity on further embryo development. A total of 2448 oocytes from 393 intracytoplasmic sperm injection (ICSI) cycles were analysed retrospectively. Oocytes were classified into 5 groups according to cytoplasmic granularity. (A) no granule or 1-2 small (<5 µm) granules; (B) more than 3 small granules; (C) large granules (>5 µm); (D) refractile body; (E) dense centrally located granular area. Correlation between characteristics of hormonal stimulation, oocyte granularity and embryo development was analysed. The occurrence of cytoplasmic granularity was influenced by the patient's age and characteristics of stimulation. The type of granulation had no effect on fertilization rate and zygote morphology. However, some type of granulation resulted in a lower cleavage rate and more fragmented embryos. Our results provided additional information on how hormonal stimulation affects oocyte quality. While cytoplasmic granularity seems not to have an effect on fertilization and embryo development, the presence of refractile body in the oocyte is associated with reduced cleavage rates and impaired embryo development.

Correlation between first polar body morphology and further embryo development.

First polar body (PB) morphology of human oocytes can indicate further embryo development and viability. However, controversial data have been published in this topic. Our retrospective study analyses the fertilization and further development of oocytes in relation to different morphological features of the first PB. The morphology of 3387 MII oocytes from 522 in vitro fertilization (IVF) treatments were assessed before intracytoplasmic sperm injection (ICSI). Oocytes were classified according to their first PB morphology. Assessment of fertilization and embryonic development (cell number, embryo grade, amount of anuclear fragmentation and presence of multinucleated blastomeres) was performed 16-20 and 42-48 hours after ICSI. Our results show that fertilization rate and embryo quality is influenced by PB morphology, while speed of development is not affected by the morphology of the first PB. Contrary to previous findings, our results suggest that oocytes with a fragmented PB had a higher developmental ability than those with an intact PB. However, we observed a lower viability of oocytes with a large PB. Since there are contradictions in this and previous observations, an extensive study is needed with standard hormonal stimulation protocol and oocyte evaluation criteria.