Treatise Upon the Genesis and Development of the Dental Follicles to the Epoch of the Eruption of the Teeth. [Volume: 2, Issue: 5, December, 1860, pp. 251-260]

GENESIS AND DEVELOPMENT OF THIE DENTAL FOLLICLES. 251

Entered, according to Act of Congress, in the year 1860, by JoNEs & WIITE, in the Clerk's Office of the
District Court for the Eastern District of Pennsylvania
TREATISE UPON THE GENESIS AND DEVELOPMENT OF THE
DENTAL FOLLICLES TO THE EPOCH OF THE ERUPTION OF
THE TEETH.
BY DRS. CH. ROBIN AND E. MAGITOT.
[Translated for the DENTAL C)SMOoS, fromn the "Jousrnl de la Physiol'gie de l'riimme et des Animux,"'
DR. E. BROWN-SMQUARD, editor, by E. SUREAU.]
~ 3. Constitution of the jaws at the time of the appearance of the
dental follicles.-The first dental bulbs appear in the human species in
the lower jaw from the fifty-sixth to the sixtieth day, and in the upper
one about the sixty-fifth day after conception; that is to say, after the
formation of the buccal cavity is completed by the union of the incisives
at the mesial line and the partition of the nose behind the dental arch.
The various tissues constituting that jaw can then be easily distinguished
from each other: first, the maxillary; second, the mucous membrane covered
with its epithelium; third, the submucous tissue, which does not differ from
the submucous tissue of the neighboring parts in regard to its anatomic
composition and its texture, but penetrates into the groove of the upper
and lower maxillaries. It is in the thick part of this that the follicles
originate.
We will consider succinctly these three parts, observing them during
the earlier periods of the fcetal age, because the phenomena of dentition
are more or less directly influenced by them.
I. THE MAXILLARIES.
When the first dental follicles appear, the ossification of the cartilage
by which the jaws originate is already much advanced throughout the
whole extent of the dental portion-the only part that it is essential for
us to consider in this place. The ossification is, however, not complete,
especially in the anterior portion, and particularly in the ruminating
animals.
The substitution of bone for cartilage being once effected, the growth
of the maxillaries continues by the method of ossification called invasion;
that is to say, in the same proportion as the cartilaginous substance is
developed at their surface, invading the surrounding submucous tissue, it
is itself conquered by ossification.
Under the microscope, at a slight increase, the bone of the maxillary,
and particularly that of the inferior, is easily distinguished from other
tissues by its dark color and the breadth of the osteoplasts, which appear
in the form of small, blackish, star-studded points. If an entire lamina