Effect of glutathione on the development of two-cell mouse embryos in vitro.

mouse embryos into blastocysts in vitro have been closely examined (Whitten, 1956, 1957; Brinster, 1965a, b, c), and it has been shown that the requirements depend on the stage of development when cultivation begins (Brinster & Thomson, 1966; Biggers, Whittingham & Donahue, 1967). One of the inter¬ esting findings has been that there is no absolute requirement for the essential amino acids either at the twoor the eight-cell stage (Brinster, 1965c; Brinster & Thomson, 1966), although the two-cell embryo does need a protein or complement of amino acids in the culture medium for development. Only when cystine was omitted from the culture medium was there a significant interference with development of the two-cell embryo. The omission of any of the other essential amino acids or amino acid constituents of bovine serum albumin did not significantly affect development. Although the eight-cell embryo can develop into a blastocyst with no fixed-nitrogen source in the medium (Brinster & Thomson, 1966), the two-cell embryo will not develop when the medium contains only a single amino acid (Brinster, 1965c). However, it did seem possible that certain groups of a few amino acids might allow development of the two-cell mouse embryo into a blastocyst, and therefore studies were undertaken to determine whether glutathione would satisfy the fixed-nitrogen requirement of the two-cell embryo.