Treatise Upon the Genesis and Development of the Dental Follicles to the Epoch of the Eruption of the Teeth. [Volume: 2, Issue: 10, May, 1861, pp. 529-535]

530

THE DENTAL COSMOS.

tissue adheres less to the groove than it does to the mucous membrane, it
can be drawn away by pulling upon the latter, and it brings with it the
follicles intact. The microscope shows that these last are not in continuity of substance with the mucous membrane, from which they are
separated by a certain depth of sub-mucous tissue. They can also be
isolated from each other without rupture. The separation between them
is proportional to the difference between the teeth of the several animal
species, and to their own proper size. Indeed, as they enlarge they
finally touch each other, except by the interposition of a remnant of submucous tissue which occurs wherever the partitions of the grooves are
yet unformed, as, for example, between the follicles of the three molars at
the time when the human foetus has attained its full growth.* They then
become contiguous to the mucous membrane, and adhere to it quite
strongly.
The bottom of the largest follicles directly touches the fasciculus of the
nerves and vessels in the lower jaw; the dental canal of this jaw is not
formed at the period of birth. Here the nerve is above, and the artery
and vein below, separated occasionally from the nerve, at the level of the
two last molars, by a thin osseous partition beyond which they enter into
the groove. As to the nerve, it is placed under the last follicle of the
molars, adhering to it as soon as it has traversed the posterior dental
foramen. t
When the follicles increase in size they each gradually assume the
general shape of the crowns, which will subsequently belong to the tooth,
with the difference that the outlines are round and not angular; in consequence of this difference the follicles of the canines and incisors are
nearly ovoid at the blunt extremity; while those of the molars are almost
* Hunter has already noticed that in the foetus of three and four months the
alveolarprocess is only a longitudinal groove, and that the vessels and nerves proceed along its bottom in a slight furrow, which afterward becomes a distinct and
complete osseous canal. He also noticed that the crests which are destined to form
the partitions extend across the canal, starting from the sides, and at first from the
anterior part of the jaws. (Hunter, Treatise upon the Teeth, 1771.) We have
already said that his successors have generally disregarded these facts. Consequently, according to Bischoff, the dental ledges become thick during the first half
of the third month, and he says that a series of round fibrous vesicles are formed there,
which are separated from each other by a compact and granulated substance. This
substance ossifies at a later period and produces the alveoli, while there originates in the
vesicle a small sack, in the bottom of which rises a small papillary projection.
(Bischoff, Treatise upon Development.) We have already seen that these phenomena do not occur in this way.
t This fact has already been exactly described and represented by M. Serres.
(Essai sur l'anatomie de la physiologie des dents. Paris, 1817. 8vo. p. 117 and fig.
8, Pl. IV.)