Effects of insulin-like growth factor-I, epidermal growth factor and cysteamine on the in vitro maturation and development of oocytes collected from 6- to 8-week-old Merino lambs.
To improve the viability of embryos produced in vitro from lamb oocytes, maturation medium was supplemented with insulin-like growth factor-I (IGF-I), epidermal growth factor (EGF), cysteamine, and combinations thereof. Experiment 1 examined the effects of IGF-I supplementation and duration of oocyte maturation on nuclear maturation and embryo development while Experiments 2 and 3 examined the effects of cysteamine and EGF supplementation respectively on embryo development. In Experiment 4, embryo development was examined after maturation with various combinations of supplements. IGF-I supplementation increased cleavage rate (P < 0.05) but its effect on the rate of blastocyst production from original oocytes was variable. Supplementation with IGF-I increased (P < 0.01) the proportion of oocytes at Metaphase II (MII) after 18 h of maturation but not at later times. EGF either alone or combined with IGF-I significantly (P < 0.05) increased cleavage rates compared with other treatment groups but EGF consistently failed to improve blastocyst production rates. Cysteamine improved hatching rates but only when supplemented alone. Maturation of lamb oocytes for 22 h in medium supplemented with 100 ng mL(-1) IGF-I and 100 microm cysteamine resulted in the production of 16.0 lambs per donor lamb after embryos were transferred to recipient ewes. It is concluded that EGF and, to a lesser extent, IGF-I, whilst beneficial to initial cleavage, can adversely influence subsequent embryo development. Improvements in embryo viability may more likely be obtained by addressing issues that influence fetal oocyte quality than by modifying in vitro methodology.
Kelly
Jennifer M
JM
South Australian Research and Development Institute, Turretfield Research Centre, Rosedale, South Australia, 5350, Australia. kelly.jen@saugov.sa.gov.au
Kleemann
David O
DO
Maxwell
W M Chis
WM
Walker
Simon K
SK
D000818:Animals; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D003543:Cysteamine / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004338:Drug Combinations; D046149:Embryo Culture Techniques; D004622:Embryo, Mammalian; D047108:Embryonic Development / Q000187:drug effects; D004815:Epidermal Growth Factor / Q000494:pharmacology*; D005260:Female; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology*; D009865:Oocytes / Q000187:drug effects* / Q000254:growth & development; D009866:Oogenesis / Q000187:drug effects*; D034561:Sheep, Domestic / Q000196:embryology / Q000502:physiology; D013997:Time Factors
D004338:Drug Combinations; D003543:Cysteamine; D004815:Epidermal Growth Factor; D007334:Insulin-Like Growth Factor I