Isozymes of lactic dehydrogenase in normal endometrium

Electrophoretic separation of the fractions of lactic dehydrogenase in normal endometrium has been described. Fractions I, II, and III predominate in the proliferative phase of the cycle, while fractions III, IV, and V are most marked in the secretory phase. Endometrium of pregnancy and that from patients using oral progestins is similar to secretory endometrium in this respect. The suggestion that fractions IV and V are those most involved in anaerobic glycolysis has likewise been discussed.