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]

GENESIS AND DEVELOPMENT OF THIE DENTAL FOLLICLES. 531

globular, or polyhedral on the round sides, and slightly convex faces.
Even when the production of the ivory has commenced, and is slightly
perceptible under the form of white spots through the wall of the follicle,
this wall is always soft, but it has also a particular kind of resistance,
which resembles that offered by a distended leather bottle.
~ 4. Thefollicular wall, in particular.-The follicular wall (PI. I.,
fig. 1, k) is fibrous and quite resistant in proportion to its thickness.
This varies in the several species of animals. At the time of the first
appearance of the ivory, the wall is only four-hundredths of a millimetre
in thickness in the hog, in which animal this wall is much easier broken
than it is in other species. At the same time it is about double this
thickness in the ruminating animals, in man, and in the carnivora. The
wall is composed of laminated fibres arranged in sheets rather than in
fasciculi, accompanied by a great number of fusiform fibro-plastic bodies,
with a certain quantity of interposed amorphous matter, and of embryoplastic nuclei.
It has at this period very clear outlines, the interior of which is marked
by a dark line, which is very distinct upon the paleness of the surrounding
tissue. The space which separates the inner face of the wall from the
surface of the bulb has increased considerably. The transparent tissue
of the organ of the enamel, which fills this space, distends the follicle,
which assumes a more or less globular form, when the happy chances of
preparation succeed in isolating it completely from the whole surrounding
tissue.
The system of vascularization in the follicular wall is very remarkable,
(P1. II., fig. 3,) and is easily observed upon the fresh embryos. The vessels emanating from the dental branch destined to each tooth spread into
the wall, from its base to its summit. The blood is not brought by a
single trunk, for we can count in the incisors or the canines two to three
arteries and as many veins.
These vessels are not contiguous, and their dimensions vary according
to the different epochs of evolution. In the human embryo of 80 to 100
days, and in the calf and lamb of six or seven weeks, the largest of the
vessels does not reach a diameter of 0'1 mill. At a more advanced period,
they become readily visible to the naked eye. The vessels slightly diverge
from the base of the follicle, and are subdivided for distribution equally
through the whole extent of the wall. Near the middle of the follicle
these vessels form a first order of polygonal meshes, which are a little
larger in the vertical direction than they are transversely. The meshes
have a diameter from three to six times greater than that of the capillaries which limit them. The vessels are a little flexuous when they
approach the gingival portion of the follicle, where they are subdivided
into ultimate capillaries, and become parallel to the great axis of the