Studies in vitro have
indicated a relatively low requirement for glucose during the early stages of embryo development
(Thompson, 2000). An embryo’s ability to utilise glucose has, however, been
linked to its developmental competence (Lequarre et al., 1997; Krisher and Bavister,
1999), thus indicating glucose to be an important substrate, since pre-morula stage embryos
require an additional energy source to lactate and pyruvate in order to reach and develop past the blastocyst stage (Leese and Barton, 1984).