-210 Nottingham - Nottingham eTheses - The University of Nottingham

3.4 DISCUSSION
The development of NT embryos is dependent on a range of factors including
coordination of donor and recipient, the cell cycle phases, reconstruction strategies,
methods of enucleation, activation, embryo culture and synchronisation of recipients.
Central to the successful development is the quality and developmental potential of
the recipient cytoplasts (oocytes). Therefore, oocyte maturation and production of
good quality oocytes is very important. The objective of these studies was to set up a
reliable and reproducible system for IVM of porcine oocytes. Ovary delivery is vital
to the porcine IVM system and ovaries collected at a slaughterhouse are the main
source of oocytes for IVM. However, it usually takes time to fetch ovaries from the
slaughterhouse to a laboratory. Temperature and time during collection and transport
are important to maintain oocyte viability. Yuge et al. (2003) suggested that exposing
porcine ovaries to a low temperature of 25°C or less before aspiration of oocytes may
adversely affect their subsequent IVM and the oocytes above 25°C at all times to
maintain fertilisability. Wongsrikeao et al. (2005) reported the storage of ovaries for
longer than 3h
impaired oocyte quality in terms of maturation and subsequent
development after IVF. Therefore, in all experiments, ovaries were collected and
maintained at 25-30°C in a thermos flask filled with DPBS and transported to the
laboratory with 1-2 h after collection.
Follicle size has been reported to influence the development of porcine oocytes. Yoon
et ad. (2000) suggested that oocytes from large follicles (3.1-8.0 mm in diameter) had
greater developmental potential than oocytes from small follicles (< 3.1 mm).
Marchal et al. (2002) found the developmental competence of porcine oocytes
increased in parallel with follicular size and a high proportion of oocytes harvested
from follicles of less than 3 mm in the pig were not fully competent for meiosis and
were cytoplasmically deficient for development. So only follicles from 3 to 8 mm in
diameter were aspirated during these studies
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