Lactate dehydrogenase isoenzyme changes during facial development.

Lactate dehydrogenase activity (LDH) was demonstrated by a histochemical technique in free, dissected, facial processes of rats from the ninth embryonic day. Facial processes of embryonic rats aged 9-15 days were analysed by isoelectric focusing for their isoenzymic distribution of LDH. A dominance of LDH-5, LDH-4 and LDH-3 isoenzymes was observed. As a comparison, LDH isoenzymes from mandibular and maxillary processes of rat embryos aged 9-11 days revealed only LDH-5 and, to a smaller extent, LDH-4. These results constitute evidence for prominent anaerobic metabolism in these tissues during early facial development. Intense staining for LDH was seen in surface epithelium, respiratory epithelium and in myogenic and osteogenic areas.