Treatise Upon the Genesis and Development of the Dental Follicles to the Epoch of the Eruption of the Teeth. [Volume: 2, Issue: 11, June, 1861, pp. 587-601]

592

THE DENTAL COSMOS.

Thus we see that there are no great difficulties in the examination of
the mode by which each of the constituent parts of the follicle originates,
or makes its first appearance. This is also the case in the study of the
ulterior phenomena of their development.
In a series of favorable preparations, we can follow all the successive
phases of the genesis, development, and atrophy of each element of the
follicular apparatus. We have seen that the dental bulb, or organ of the
enamel, is the first to appear, and we have recognized it at its commencement as a small, conical mass, trenching by its opacity upon the surrounding tissues. The first rudiments of the follicular wall afterward show
themselves around this little mass, and when this wall completely surrounds
the bulb, the organ of the enamel appears between them.
Such are the facts of the evolution and the constitution of the follicle
in man and most of the mammiferae. But we will find hereafter that in
certain species, the pachydermata, for example, the follicle contains another
organ filling a special office. This organ is the germ of the cement,
formed of a soft, vascular fibrocartilage, and which changes the tissue, of
which the cement is constituted, into the condition of bone properly so
called.
On what point of this completed follicle should the constituent elements
of the tooth, properly so called, appear? It is at the summit of the
simple or multiple papillae of the germ of the ivory, in the most superficial bed of the organ, and consequently, beneath the deep face of the germ
of the enamel-here the first cells of the ivory are produced, and to them
succeeds the little cap of dentine. The development of the ivory then
gives rise to the separation of the two germs, of the ivory and the enamel,
with the atrophy of the latter. This separation is still more increased by
the ulterior phases of the evolution and of the thickening of the bed of
ivory.
This first appearance of the tooth, properly so called, answers in man,
according to our observations, to a period varying between the eightieth
and eighty-fifth day, and it takes place primitively in the heart of the
follicle of the lower middle incisor.
CHAPTER III.
STRUCTURE OF THE PRODUCTIVE ORGAN8 OF THE TOOTH, GENESIS AND DEVELOPMENT
OF THE TISSUES WHICH COMPOSE IT.
THE dental follicle, considered as a whole, has reached the period of
complete development at the moment when the phenomena of genesis and
development of the tissues constituting the tooth (ivory, enamel, and
cement) exhibit themselves. Each of the parts of which it is composed
has been subjected to modifications of intimate structure, the accomplishment of which precedes the debut of its physiological rdle. We will