Oocyte metabolism predicts the development of cat embryos to blastocyst invitro

Current methods for detecting complete oocyte maturation and developmental competence are inadequate. The objectives of this study were to (1) examine the relationship between cat oocyte energy metabolism and development in v itro after fertilization and (2) determine if cumulus cell metabolism could be used to predict development of individual oocytes after fertilization i n vitro. The hanging drop method was used to assess metabolism of three dif ferent types of cat oocytes: immature (IMO), in vitro matured (IVM), and in vivo matured (IVOM). Stage of oocyte nuclear maturation or developmental c ompetence was assessed after metabolic analysis, Glycolysis and oxidation o f glucose, glutamine, palmitate, and lactate increased with the resumption of oocyte meiotic maturation (P < 0.05). Pyruvate was the preferred substra te, but uptake was not linked to maturation. IVM oocytes had impaired gluco se and palmitate metabolism compared to IVOM oocytes (P < 0.05). Oocyte gly colytic activity and oocyte glucose oxidation correlated well with embryo d evelopment after insemination in vitro (P < 0.05). Furthermore, oocytes tha t had similar glucose metabolism and that were grouped together for culture on this basis had higher (P < 0.05) overall rates of development than oocy tes grouped randomly. There was no correlation (P > 0.05) between cumulus c ell metabolism and individual oocyte development after in vitro fertilizati on. The data reveal that energy metabolism is linked to oocyte maturation i n the cat and that glucose metabolic activity can indicate those oocytes mo st likely to fertilize and develop in vitro. Measuring cumulus cell metabol ism does not accurately predict individual oocyte development after insemin ation in vitro. Mel. Reprod. Dev. 56:163-171, 2000. (C) 2000 Wiley-Liss, In c.