Page 127 - My FlipBook

DENTIN. 125

give off a great many fine brandies passing through the matrix in all
directions from tubule to tubule. These branches are so numerous that
in sections which have been mounted in such a way as to leave air in
them, or if the tubules have been filled with coloring-matter, they give
the impression of looking through a hazel bush ; or they may be likened
to the fine rootlets of a plant. These fine branches are shown in
Fig. 105, and the character of the dentin in the root portion is to be
compared with that in the crown portion as shown in Fig. 102. The
Fig. 108.

Granular layer of Tomes: i, lacunae of cementum ; G/, granular layer of Tomes; 7gi, interglobular
spaces. (About 200 X.)
outermost layer of the dentin next to the cementum contains many
small irregular spaces, which connect with the dentinal tul)ules and give
to the tissue when seen with low powers a granular a])]K'arance. This
layer was first described by John Tomes as the granular layer, and has
since been usually called the f/r(inu/(ir layer of Toiiief^. The spaces of
the granular layer are probably filled by the enlarged ends of the den-
tinal fibrils. The same appearance is sometimes seen beneath the enamel,
but is never as well marked as next to the cementum.
The dentin at the dento-enamel junction seldom presents a smooth
surface, but the inner surface of the enamel plate shows rounded pro-