Thiamine pyrophosphatase activity of the prenatal mouse molar. A histochemical investigation

Thiamine pyrophosphatase (TPPase), an enzyme associated with the Golgi apparatus, has been implicated in the regulation of cellular oxidation as well as of transport across cell membranes. This enzyme has been localized in odontogenic tissues of the postnatal mouse and it was the intent of the present study to localize TPPase during prenatal odontogenesis. Mouse fetuses (CDI, Charles River) 14 through 19 days postconception were decapitated, the heads were frozen and mounted on the chuck of a cryostat. Frontal sections, 14 micrometers thick, were air-dried and incubated for TPPase activity. Subsequent to incubation the activity was visualized by immersion in 1% ammonium sulfide. The degree of enzyme activity varied not only with the chronological age of the fetus but also as a function of the tissue's metabolic state. Regions, such as the dental lamina, evidenced decreased TPPase activity with increasing age, while tissue layers such as the IEE displayed greater enzyme activity with increasing age.