Hi Group 8! Thank you for that insightful question!
Among all the molecular factors that regulate the mucification/expansion of cumulus cells, GDF9 (growth differentiation factor-9), BMP15 (bone morphogenetic protein-15), and the presence of the oocyte itself are the main factors involved in the process. GDF9 and BMP15 are known as cumulus expansion enabling factors (CEEFs). They stimulate the expression of the other transcripts mentioned in the video, including Has2, Tnfaip, Ptx3 and Ptgs2. Therefore, without the two factors, cumulus expansion will not be initiated at all. This may eventually lead to female infertility, as evidenced by some studies (Elvin et al., 1999; Yoshino et al., 2006).
On the other hand, presence of the oocyte itself is also necessary for cumulus cell differentiation and expansion. In oocytectomy procedures (OOX), where fully-grown oocytes are removed from the oocyte-cumulus complex, cumulus cells were observed to dedifferentiate. This entirely prevents the mucification and further development of cumulus cells. Despite all this, each molecular factor that regulates cumulus cell mucification is important for normal oogenesis to occur. Mutations or deficiencies in any of these factors will definitely have deleterious effects on the developing oocyte.
Among all the molecular factors that regulate the mucification/expansion of cumulus cells, GDF9 (growth differentiation factor-9), BMP15 (bone morphogenetic protein-15), and the presence of the oocyte itself are the main factors involved in the process. GDF9 and BMP15 are known as cumulus expansion enabling factors (CEEFs). They stimulate the expression of the other transcripts mentioned in the video, including Has2, Tnfaip, Ptx3 and Ptgs2. Therefore, without the two factors, cumulus expansion will not be initiated at all. This may eventually lead to female infertility, as evidenced by some studies (Elvin et al., 1999; Yoshino et al., 2006).
On the other hand, presence of the oocyte itself is also necessary for cumulus cell differentiation and expansion. In oocytectomy procedures (OOX), where fully-grown oocytes are removed from the oocyte-cumulus complex, cumulus cells were observed to dedifferentiate. This entirely prevents the mucification and further development of cumulus cells. Despite all this, each molecular factor that regulates cumulus cell mucification is important for normal oogenesis to occur. Mutations or deficiencies in any of these factors will definitely have deleterious effects on the developing oocyte.
References:
Elvin, J. A., Clark, A. T., Wang, P., Wolfman, N. M., & Matzuk, M. M. (1999). Paracrine actions of growth differentiation factor-9 in the mammalian ovary. Molecular Endocrinology, 13(6), 1035–1048. https://doi.org/10.1210/mend.13.6.0310
Yoshino, O., McMahon, H. E., Sharma, S., & Shimasaki, S. (2006). A unique preovulatory expression pattern plays a key role in the physiological functions of BMP-15 in the mouse. Proceedings of the National Academy of Sciences, 103(28), 10678–10683. https://doi.org/10.1073/pnas.0600507103