Research Achievements Bovine oocytes increase in diameter from 30 µm to 125 µm, and an antrum is formed inside the follicles. Bovine growing oocytes of >100 µm are able to resume meiosis, although they are incompetent to mature to metaphase II. Thus, their precocious resumption of meiosis during growth culture makes it difficult for them to grow to full meiotic competent oocytes.

i) PDE3 inhibitors induced formation of antrum-like structures by oocyte-granulosa cell complexes (OGCs) and maintained meiotic arrest of oocytes during culture. Since formation of the antrum-like structures was promoted with the inhibition of PDE3, which is functional only in oocytes, I thought that the PDE3 inhibitors might promote expression of some oocytes-derived factors, which in turn induce the formation of antrum-like structures.

ii) OGCs developed antrum-like structures, whereas oocytectomized complexes (OXCs) and granulosa cell complexes (GCs) did not develop the structure. However, GDF9 and BMP15 induced formation of antrum-like structures in OXCs and GCs. To complete the hypothesis, I examined the effect of PDE inhibitors on the expression of GDF9 and BMP15 mRNAs in in vitro grown bovine oocytes.

iii) The relative mRNA levels of GDF9 and BMP15 increased in the oocytes after culture with PDE3 inhibitors.

From these studies, I found that inhibition of oocyte PDE3 maintained meiotic arrest of oocytes and increased expression of GDF9 and BMP15 mRNAs. The oocytes induce formation of antrum-like structures by the granulosa cells via oocyte-derived factors, GDF9 and BMP15.

1. Islam MN, Alam MH, Khatun A, Hashem MA, Moniruzzaman M. Kit ligand enhances growth and nuclear maturation of buffalo oocytes in vitro. 45^th IETS Annual Conference, New Orleans, USA, 2019.
2. Alam MH, Lee J, Miyano T. GDF9 and BMP15 promote antrum formation by bovine cumulus cells in vitro. The 124^th JSAS Annual Meeting, Tokyo, Japan, 2018.
3. Alam MH, Lee J, Miyano T. Effect of PDE inhibitors on growth and maturational competence of partially meiotic-competent bovine oocytes in vitro. 4^th World Congress Of Reproductive Biology, Okinawa, Japan, 2017.
4. Mamun SA, Alam MH, Sarker MB, Khatun A, Hashem MA, Kabir AKMA, Moniruzzaman M. Role of dibutyryl cyclic adenosine 3´5´ monophosphate on growth and survival of buffalo oocytes. Proceedings of 9^th Biennial Conference and International Seminar 2015 organized by Bangladesh Animal Husbandry Association (BAHA), Bangladesh, 10-11 December 2015, 116.
5. Miraz MFH, Kabir ME, Alam MH, Sarker MB, Khatun A, Khandoker MAMY, Husain SS, Moniruzzaman M. Effects of dietary energy levels on follicular development and oocyte maturation in Black Bengal goats. Proceedings of 9^th Biennial Conference and International Seminar 2015 organized by Bangladesh Animal Husbandry Association (BAHA), Bangladesh, 10-11 December 2015, 121.
6. Sarker MB, Alam MH, Saha BK, Amin MR, Moniruzzaman M. Effects of feeding soymilk based milk replacer on growth and rumen development in kids. Proceedings of the 30^th Biennial Conference of the Australian Society of Animal Production, Canberra, Australia, 2014.
7. Islam MM, Sarker MB, Alam MH, Khan RI, Moniruzzaman M. Germination test of wheat for pregnancy diagnosis of goats and sheep. Proceedings of the 16^th AAAP Animal Science Congress Vol. II, Yogyakarta, Indonesia, 2014.
8. Kabir ME, Alam MH, Sarker MB, Saha BK, Khandoker MAMY, Moniruzzaman M. Effects of dietary energy levels on ovarian follicular morphology of goats. 11^th World Conference on Animal Production Proceeding, Beijing, China. 311, 2013.
9. Alam MH, Sarker MB, Kabir ME, Saha BK, Khan MRI, Moniruzzaman M. Ovarian follicular development of goats in different feeding systems. 3^rd Annual Conference and Seminar 2013, organized by Bangladesh Society for Animal Production Education and Research (BSAPER), Dhaka, Bangladesh, 46.
10. Saha BK, Sarker MB, Alam MH, Kabir ME, Amin MR, Moniruzzaman M. Reproductive performance of rabbit does and growth of kids in different postpartum re-mating intervals. 3^rd Annual Conference and Seminar 2013, organized by Bangladesh Society for Animal Production Education and Research (BSAPER), Dhaka, Bangladesh, 46.
11. Islam MM, Sarker MB, Alam MH, Saha BK, Khan MRI, Moniruzzaman M. Seed germination test for pregnancy detection in sheep. 3^rd Annual Conference and Seminar 2013, organized by Bangladesh Society for Animal Production Education and Research (BSAPER), Dhaka, Bangladesh, 47.
12. Sarker MB, Alam MH, Saha BK, Miraz MFH, Amim MR, Moniruzzaman M. Effects of feeding soymilk-based milk replacer on growth and rumen development in kids. 3^rd Annual Conference and Seminar 2013, organized by Bangladesh Society for Animal Production Education and Research (BSAPER), Dhaka, Bangladesh, 56.