Blastocyst enzyme activity

Enzymes with an initially low activity which gradually increased during embryonic development. To this group of enzymes belong fructose-1,6-diphosphate aldolase (FDP-aldolase) and NAD-dependent malate dehydrogenase (NAD-MDH). The activities of these enzymes increased gradually until the morula-blastocyst transition, whereupon the enzyme activity increased more rapidly (Epstein et al., 1969). 

It cannot be ruled out that RNA transcription is unimportant for normal development prior to blastocyst formation. The fertilized egg contains many enzymes, and the activity of these has been shown to change considerably through preimplantation development. For example, the activity of hypoxanthine-guanine phosphoribosyltransferase, adenine phosphoribosyltransferase, and hexokinase increases markedly from the fertilized egg to the blastocyst stage (Brinster, 1968a Epstein, 1970) ... 

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