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82 EMBRYOLOGY OF THE DENTAL TISSUES.

numbers, and lose their individuality by merging into one another, form-
inf hirger globules, of various shapes and sizes (Fig. 64), seeming to
take into their substance portions of the odontoblast. These globules
enlarge until they reach their typal width, expand laterally, meeting
and coalescing with others. The minute glol)ules are seen within the
odontoblasts of different sizes, all having a glistening appearance, some-
thing like fat globules in cells. The early layers formed by the glol)-
ules are about the width of the band of formative cells. (See Figs.
65, 66, 67).
CALCIFICATION OF THE ENAMEL,
The statement made by Tomes and others that enamel is formed
by the actual conversion of the enamel cells into the enamel rods is an
erroneous one. The enamel cell does not calcify ; it superintends the
laying down of calcific material which is to form the rod. For the
earliest deposit of enamel the calcium salts are stored in the meshes
of the so-called stellate reticulum, and as the first enamel forms, the
enamel organ proper disapjjears at this point. Only the two inner-
most layers remain ; these are the layer of the columnar cells (amelo-
blasts) over the forming enamel, and a layer of cells somewhat resem-
bling connective-tissue cells (the stratum intermedium) over these. The
two layers are separated by Avhat
^^^- ^^' appears to be a line of tissue which
has been called a membrane. The
embryonic connective tissue of the
jaw is now in direct communication
with the stratum intermedium, and
_ a rich blood supply is developing
near the point of juncture. The
function of the cells of the stratum
intermedium is supposed to be the
supplying of new cells to the amelo-
'^
blastic layer as they may be needed by
the increase in the circumference of
Section of i.u, n.u, .1, fJw.ing tooth, showing the enamel, as new enamel is formed ;
calcification of enamel 1, globules of cai-
: ^^ furnish the Organic fluid in M-hich
co-globulin deposited on dentin cusps ^ i • i
from the enamel cells; 2, dentin (the the calcium Salts are deposited;
enamel cells have been cutaway in prepar-
^^^j ^^ supplv the fine network of
ing the section). i i . i . i
fibers, the scaffolding upon wdiich
the enamel rods are to be built. Prof. Sudduth is the authority for
the statement that enamel is nothing more or less than a coat of mail
supplied by Nature to protect the dentin.
Enamel cells that have been properly prepared and not shrunken
will be seen filled with minute globules. The authorities who speak of