Development of Sheep Embryos in Vitro in a Medium Supplemented with Different Serum Fractions

Abstract

Sheep embryos will generally develop into expanded blastocysts in vitro only in culture media supplemented with serum or serum components. In order to better understand how serum supports embryo development, a batch of ovine serum was fractionated by (a) ultrafiltration into two components containing substances with molecular weights greater and less than 10 Kd (kilodaltons), and (b) gel filtration into protein fractions 1, 2 and 3, containing groups of proteins with mean molecular weights of about 500, 150 and 65 Kd, respectively. The principal protein in fraction 3 was albumin. Day 6 sheep morulae were cultured in vitro for 48 hours in a bicarbonate-buffered salt solution supplemented with various concentrations of ovine serum or of these components or protein fractions of serum.