OF NON-VASCULAR ANIMAL TISSUES. 
177 
structure. They, like the fibro-cartilages of symphyses, consist of an external fibrous 
and of a central cartilaginous portion. At the early periods of their development, the 
cartilaginous is more abundant than the fibrous portion, and it is almost entirely 
composed of corpuscles. As age advances, the fibrous portion increases in quantity ; 
and towards the later periods of life, the corpuscles of the cartilaginous division are 
mixed with fibrous tissue. 
Of the Vessels of Fibro- Cartilage. 
Respecting the vascularity of the fibro-cartilages, Bichat says, “ Peu de sang pe- 
nktre leur systkme vasculaire dans l’etat ordinaire, mais dans l’inflammation ils sont 
extremement injectes*.” 
Professor Todd says, “ They (the fibro-cartilages) are more vascular than pure car- 
tilage, but in the natural state they admit very few vessels carrying red blood -f-.” 
Muller, as quoted above, says “they have blood-vessels, although in a small 
number.” 
Of the Vessels of Fibro-Cartilages of the First Class. — 1. Of the inter-vertebral 
substances. — I have made numerous injections of the intervertebral substance in Man 
and animals of various ages, and have found that the external more fibrous portion 
is pierced by arteries of considerable size ; these are guarded from compression by 
the dense nature of the fibrous tissue through which they pass. They course towards 
the central cartilaginous portion, into which, however, they do not penetrate, but in 
its confines they form large convoluted dilatations, from which the recurrent vein 
arises. The extreme edge of these vascular convolutions presents a line which may 
be considered as the boundary between the fibrous and cartilaginous portions of the 
intervertebral fibro-cartilage. See Plate XV. fig. 6. 
2. The following is the result of a careful examination of the vessels of the sacro- 
iliac jibro-cartilage in the human subject, at various periods of its development. 
a. In the ffth month of foetal existence the vessels of the sacro-iliac fibro-cartilage 
form a conglomerated mass of large and tortuous arteries and veins contained in the 
external part of the fibrous portion. Here and there a few more delicate branches 
diverge from this mass to a slight distance towards the central cartilaginous portion, 
at the border of which they terminate in dilated extremities. 
b. In the foetus of six months the convoluted arteries are prolonged to the circum- 
ference of the cartilage, where they divide and subdivide, each branch terminating in 
a dilatation, which frequently communicates with the one adjacent to it, and from 
this dilatation or series of dilatations the recurrent veins arise. 
c. In the foetus of nine months these vessels are considerably increased in length ; 
they are more distant from each other, and their extremities no longer present the 
large dilatations. 
* Anatomie Generate. Article, Organization du Systbne Fibro-Cartilagineux. 
t Cyclopsedia of Anatomy and Physiology. Article, Fibro -Cartilage. 
