ABSTRACT
The optimal concentrations of a variety of components for promoting growth of 5-day-old rabbit blastocysts in vitro were determined. Growth, under different modifications of the basic medium (F10 plus 15 per cent, maternal rabbit serum) was expressed as the tangent of the growth curve plotted after 4 hr. and 24 hr. of incubation, where the average normal in vivo tangent is equal to 1.
Improved growth was observed with limited increase in the concentrations of glycine, alanine, glutamic acid, threonine, serine and pyruvate, with the addition of lactate and a reduction in concentration of glucose. Addition of glycogen made a slight improvement in growth but linoleic acid suppressed growth.
The effective concentrations of pyruvate and serine appear to be mutually interdependent.
From the optima so revealed, the F10 medium was modified. This modified F10 medium alone supports good growth of 5-day-old blastocysts but when serum is added to 5 per cent., growth is within the range of that occurring in vivo.