-210 Nottingham - Nottingham eTheses - The University of Nottingham

synchronisation is to cause a temporary block to meiotic progression during porcine
oocyte maturation and then to remove the block, allowing the oocytes to fulfill
maturation in vitro. In the third experiment, I compared oocyte maturation following
treatment with CHX or cAMP in order to determine their effects on synchronisation
of maturation and subsequent development for the use in SCNT. The objectives were
to determine which inhibitor allowed oocyte maturation to proceed producing MII
oocytes in the smallest determined period.
Our observations in porcine conventional IVM confirmed that the meiotic progression
of porcine oocytes in vitro is asynchronous. This was consistent with Motlik and
Fulka (1976), Funahashi et al. (1997b) and Ye et al. (2005). Oocytes were not only at
various GV and later stages prior to in vitro maturation but also asynchrony persisted
throughout the entire culture period.
The CHX protocol was based on previous studies reported by Ye et al. (2005). The
length of exposure to 5 gg/m1 CHX was 12 h and hormones (10 IU/ml PMSG and 10
IU/ml hCG) were added throughout the maturation period. Ye et al. (2002) showed
these were the optimised concentration and duration of CHX treatment for arresting
porcine oocytes at the GV stage compared to 0.1,1 and 25 µg/ml CHX and 24 h. The
concentration of cAMP used was at 1 mM and oocytes were released from both
cAMP and hormones at 22 h. This was based on Betthauser et al. (2000) and
Funahashi et al. (1997b). This study agreed with Ye et al. (2005) and Betthauser et al.
(2000) that CHX and cAMP can synchronise the porcine oocytes and the meiotic
inhibition was reversible.
Many cytoplasmic changes, termed cytoplasmic maturation, occur with nuclear
maturation. Both nuclear maturation and cytoplasmic maturation are important for
embryo development (Sun et al., 2001). However, cumulus expansion
has been
suggested to be functionally related to the nuclear and cytoplasmic maturation of the
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