Role of Cumulus Cells and Follicular Fluid on Oocyte Maturation and Developmental Competence of Embryos: Intact and Reconstructed Oocytes

Changes in Nucleus and Cytoplast During Oocyte Maturation: Involvement in Embryo Production

“…The previous results demonstrated that meiotic maturation of GV cytoplasts reconstructed with embryonic/somatic cells (G0/ G1 or G2/M stage) were associated with abnormalities in earlier extrusion of 1 st polar body, chromosomal alignment over spindle and condensation, and cytokinesis (Figures 4 and 5;Mohammed 2006). Our trials to overcome and to explore such abnormalities have been reported (Mohammed 2006;Mohammed et al, 2022;Al Zeidi et al, 2022). Such previous trials improved the competence of enucleated GV cytoplast after embryonic/somatic nuclear transfer followed by maturation and activation/fertilization.…”

“…Enrichment of maturation media with cumulus cells (Al Zeidi et al, 2022), growth factors and hormones (Bunel et al, 2020;Ko et al, 2021;Kumar et al, 2020;Wolff et al, 2022), and other factors (Martínez-Quezada et al, 2021;Zabihi et al, 2021;Saini et al, 2022;Chelenga et al, 2022) improves oocyte maturation and embryo development thereafter (Gordon 2003;Baruffi et al, 2004;Somfai et al, 2012). In addition, super-stimulation of ovarian follicles via gonadotropin injections resulted in changes in small, medium, and large follicles according to the number and dose of gonadotropin injections and side of the ovary (Abdelnaby et al, 2021).…”

“…Fully-grown germinal vesicle (GV) cytoplasts could be divided through two consecutive meiotic divisions; first and second meiotic divisions if cultured in vitro. The hypothesis that the GV cytoplasts are able to divide G0/G1 or G2/M nucleus through first and second meiotic divisions, respectively (Mohammed, 2006;Mohammed, 2014a;Mohammed et al, 2014b;Mohammed et al, 2010;Mohammed et al, 2019a;Mohammed et al, 2022;Al Zeidi et al, 2022). Therefore, GV nuclei, male germ cells, embryonic and somatic cells at G0/G1 or G2/M stage might divide correctly in the GV cytoplasts through 1 st and 2 nd meiotic divisions, respectively to solve the problem of infertility as ageing-associated chromosome misalignment in meiosis of oocytes from the aged mice or studying reprogramming of the introduced nuclei or nucleolar dysfunction (Fulka et al, 2004;Mohammed et al, 2022;Al Zeidi et al, 2022).…”

“…The hypothesis that the GV cytoplasts are able to divide G0/G1 or G2/M nucleus through first and second meiotic divisions, respectively (Mohammed, 2006;Mohammed, 2014a;Mohammed et al, 2014b;Mohammed et al, 2010;Mohammed et al, 2019a;Mohammed et al, 2022;Al Zeidi et al, 2022). Therefore, GV nuclei, male germ cells, embryonic and somatic cells at G0/G1 or G2/M stage might divide correctly in the GV cytoplasts through 1 st and 2 nd meiotic divisions, respectively to solve the problem of infertility as ageing-associated chromosome misalignment in meiosis of oocytes from the aged mice or studying reprogramming of the introduced nuclei or nucleolar dysfunction (Fulka et al, 2004;Mohammed et al, 2022;Al Zeidi et al, 2022). In case of male infertility due to complete absence of the germline, GV cytoplast could be reconstructed with germ cell of male in order to create "artificial oocyte" containing the male haploid genome of the fused germ cell after in vitro maturation.…”