The ultrastructure of enamel from the kangaroo macropus giganteus: Tubular enamel and its 'black spots' defect

Abstract

A study of the enamel of M. giganteus by light microscopy and transmission electron microscopy on specimens prepared by argon-ion-beam thinning showed that normal tubular enamel consisted of closely packed long lath-like crystals of hydroxyapatite, thickness range 30-50 nm and width range 50-90 nm, and a micropore structure similar to that in human enamel. Enamel tubules, roughly circular in crosssection of approximately 0.2-1 -5 μm diameter, and spaced 2-9 μm apart, were a common feature of tubular enamel and were not confined to any particular prism. Within the tubular enamel there were pockets of defective enamel containing: (1) big crystals (∼250 nm diameter) of hydroxyapatite, whitlocki..