Fractionated serum dialysate and synthetic media for culturing 2- and 4-cell rabbit embryos.

Abstract

Embryos in the 2- and 4-cell stage were cultured for 4 days in a simple glucose-salt solution with 1.5% crystallized bovine serum albumin (BSA) to which were added fractions of freeze-dried bovine blood serum dialysate separated on G-25 and G-10 Sephadex columns. Development of 1389 embryos was compared in 35 treatments. The fractions which promoted blastocyst formation had a molecular weight of less than 700. Most of the amino acid content of the unfractionated dialysate was found in the active fractions, thus implicating amino acids as being important additions to the simple synthetic medium. In the absence of BSA no blastocysts formed in the simple synthetic medium containing serum dialysate, or in a “complete medium” formed by adding a complement of amino acids, vitamins, and trace minerals to the simple medium. The addition of serum dialysate to the complete medium resulted in 4.5% of the embryos reaching the expanding blastocyst stage as contrasted with 69.8% when 1.5% BSA was added. The combined addition of serum dialysate and BSA to the simple medium resulted in 22.6% expanding blastocysts. These studies suggest the need for a macromolecular component (BSA) and indicate that the serum dialysate did not provide as optimum a balance of amino acids and other nutrients as were provided by the complete synthetic medium.