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Title: Follicle oocyte interactions and embryo development in the bovine : an in vitro study
Author: Fouladi-Nashta, A. A.
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 1999
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In systems currently employed for the production of bovine embryos in vitro, the frequency of development to the blastocyst stage and subsequently production of live offspring is lower than that observed in vivo. Typically for in vitro maturation and fertilization oocytes are aspirated from a wide range of follicle sizes (2-8 mm in diameter). Oocytes increase in size with enlargement of the follicles, and those from larger follicles have a higher developmental competence. This suggests that oocytes from small antral follicles may be deficient in some vital factor/s which are important for embryonic development. In vivo, oocytes remain arrested at the germinal vesicle (GV) stage until hormonally stimulated. In contrast, when aspirated from follicles in vitro, they are released from the inhibitory function/s of the follicle wall and develop to the second metaphase (MII) stage. It was hypothesised that if oocytes are cultured in vitro in conditions which maintain GV arrest, then the oocyte may have the opportunity to synthesise or modify factors which are required for embryonic development. A culture system was established in which intact large antral follicles of 4-8 mm in diameter remained viable for up to 7 days. The majority of oocytes (96.8%) recovered following 24 hours of follicle culture remained arrested at the GV stage. On removal from the follicle and transfer to a suitable medium, 80% of these oocytes resumed meiosis and developed to the MII stage. However, with increasing periods of follicle culture, both the number of GV arrested and MII matured oocytes was significantly reduced. Follicle culture for a period of 24 hours was used for the all subsequent experiments. Follicle culture derived oocytes resulted in a significantly higher rate of blastocyst production than directly aspirated oocytes.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available