Behaviour of cytoplasmic organelles and cytoskeleton during oocyte maturation

Abstract

Assisted reproduction technology (ART) has become an attractive option for infertility treatment and holds tremendous promise. However, at present, there is still room for improvement in its success rates. Oocyte maturation is a process by which the oocyte becomes competent for fertilization and subsequent embryo development. To better understand the mechanism underlying oocyte maturation and for the future improvement of assisted reproduction technology, this review focuses on the complex processes of cytoplasmic organelles and the dynamic alterations of the cytoskeleton that occur during oocyte maturation. Ovarian stimulation and in-vitro maturation are the major techniques used in assisted reproduction technology and their influence on the organelles of oocytes is also discussed. Since the first birth by assisted reproduction treatment was achieved in 1978, numerous techniques involved in assisted reproduction have been developed and have become attractive options for infertility treatment. However, the unsatisfactory success rate remains as a main challenge. Oocyte maturation is a process by which the oocyte becomes competent for fertilization and subsequent embryo development. Oocyte maturation includes both nuclear and cytoplasmic maturation. Nuclear maturation primarily involves chromosomal segregation, which has been well studied, whereas cytoplasmic maturation involves a series of complicated processes, and there are still many parts of this process that remain controversial. Ovarian stimulation and in-vitro maturation (IVM) are the major techniques of assisted reproduction. The effect of ovarian stimulation or IVM on the behaviour of cell organelles of the oocyte has been postulated as the reason for the reduced developmental potential of in-vitro-produced embryos. To further understanding of the mechanism of oocyte maturation and future improvement of assisted reproduction treatment, the complex events of cytoplasmic organelles and the cytoskeleton that occur during oocyte maturation and the influence of ovarian stimulation and IVM on these organelles are described in this review.

Pretreatment of in vitro matured bovine oocytes with docetaxel before vitrification: Effects on cytoskeleton integrity and developmental ability after warming

“…This may be a reason why docetaxel pretreatment increases the rate of normal MC distribution in vitrified oocytes. Furthermore, it has been proven that the movement of MC within different areas of oocytes is mediated by a CSF network of MT in mouse [27,46] and pigs [43]. Therefore, damage of MT during vitrification might affect the movement of MC within oocytes.…”

Ultrastructure changes in buffalo (Bubalus bubalis) oocytes before and after maturation in vitro with sericin

“…), protein synthesis and RNA transcription (Mao et al . ). During the transition from the germinal vesicle to the metaphase II stage, the ultrastructure of bovine oocytes, such as mitochondria, ribosomes, endoplasmic reticulum, cortical granules and the Golgi complex, was rearranged (Ferreira et al .…”

Ultrastructural changes in oocytes during folliculogenesis in domestic mammals

“…Of course, all those morphological changes happen concomitantly with biochemical and molecular modifications (for details see [114],[116]), which lead the oocytes to nuclear and cytoplasmic maturation and guarantee their competence to be fertilized.…”