Uptake of tricarboxyli acid cycle intermediates by preimplantation mouse embryos in vitro.

Preimplantation mouse embryos were incubated for various periods in the (14)C-labeled intermediates of the tricarboxylic acid cycle, malate, citrate, or 2-oxoglutarate. A marked increase in uptake of these substrates first occurred at the 4-cell stage, the uptake increasing with the length of incubation and the developmental stage of the embryo. In the light of recent observations on ultrastructural changes in mouse embryos with development, studies of mitochondrial transport systems, and the growth of metabolic activities in developing mouse embryos, the increase in accumulation of the tricarboxylic acid cycle intermediates with development may indicate fundamental changes in mitochondrial function that is necessary for further development.