Effects of excess glucose on mammalian post-implantation embryos

Studies on the effects of excess glucose on mammalian post-implantation embryos grown in culture are reviewed and selected examples of these studies are discussed to demonstrate the value, and the limitations, of the embryo-culture system. By use of culture techniques the precise concentrations of exogenous glucose causing morphological and biochemical changes are defined for a range of developmental stages in both rat and mouse embryos. The critical window of exposure is known and the morphological, cellular and biochemical changes associated with hyperglycemic culture are described. The effects of hyperglycemic serum are briefly compared with those of serum prepared from diabetic rats and the contribution of the high glucose concentrations to the embryopathic effects of the "diabetic" serum is assessed. The advantages and the limitations of the culture system are discussed.