Temporary cartilage, 
with corpuscle arran- 
oy of the corpus- 
_ parietes of the cor- 
OSSEOUS TISSUE. 
temporary cartilage on the approach of ossifi- 
cation is that the corpuscles, instead of being 
solitary, are arranged in groups of variable 
numbers according as they are near or far off the 
site of immediate ossification ; that they have 
a linear arrangement, and where there are two 
or three only this is somewhat semilunar, with 
the straight edges near each other ; and that the 
greatest diameter is lateral. (See fig. 457, 0.) 
Moreover, the columns are not continued unin- 
terruptedly through the cartilage, but are broken 
off, and near their terminations new ones com- 
mence, not, however, in a line with the former, 
but opposite their intercolumnar spaces. (See 
fig. 458.) 
Supposing this view of 
the subject to be correct, as 
I believe it to be, the growth 
of a bone in its length ad- 
mits of easy solution, name- 
ly, by the developement of 
cartilage at the epiphyses. 
The formation of co- 
lumns having commenced, 
developement in the lines 
proceeds with rapidity, and 
the corpuscles composing 
them hold a different rela- 
tion to each other at each 
rt of the same column. 
us atthe end farthest from 
the point of ossification the 
corpuscles are flattened and 
closely arranged, present- 
ing an appearance not un- 
ie. like a pile of pence. Butas 
we trace the line down. to- 
Fig. 458. 
ged in columns. — 
a, intercolumnar 
or cellular tissue ; 5, 
puscle; c, central 
_ wards the bone, each corpuscle becomes more 
distinct, is separated from those on either side, 
_ becomes itself enlarged, and of nearly equal 
' dimension in each direction. (See figs. 458 and 
460.) The intercellular tissue becomes distinctly 
- visible between each corpuscle. The space also 
between the columns, though always consider- 
able, is increased when the corpuscles have 
“undergone the above change. (See fig. 459.) 
a4 
bs Fig. 459. 
of the intercellular or hyaline substance, the 
‘corpuscle having been removed. * 
ot only are the described changes in form 
855 
and relative position observable, but a further 
remarkable developement-takes place in each 
corpuscle. The parietes of the cell, which at 
first formed but a small part of the whole, at 
this latter situation has so far increased in di- 
mension that it forms by far the greater part of 
the mass, while the central portion, which at 
first appears to constitute the whole corpuscle, 
notwithstanding its increase of size, is now to be 
regarded only as a nucleus, presenting the ap- 
pearance of a cavity or granular cell, of a form 
approaching that of a sphere. (See fig. 460.) 
Cartilage, when it has 
been subject to the 
above changes, in the 
nexttransition becomes 
bone. In order to un- 
derstand this process 
it will be necessary to 
bear in mind the fol- 
lowing points: first, 
that the enlarged carti- 
lage corpuscles are ar- 
ranged in vertical co- 
lumns; that each co- 
lumn is surrounded by 
the intercellular tissue, 
Section of temporary car- 
tilage, which has under- 
gone the last stage towards 
ossification. 
a, intercolumnar tis- 
sue ; 6, the enlarged pa- 
rietes of corpuscle; ¢, 
central nucleus of the 
corpuscle. 
and that each corpuscle 
is separated from those 
above and below by a 
layer of intercellular 
tissue; and, lastly, that 
each corpuscle has dis- 
tinct parietes with cen- 
tral nucleus, or cavity, 
containing granules or 
having granular parie- 
tes. Osseous tissue is in all instances developed 
in the form of minute granules, so the earliest 
appearance of bone in cartilage is marked by 
the presence of these spherical granules in the 
intercolumnar and intercellular tissue, which is 
thereby increased in density and opacity. This 
constitutes the first stage in the process of the 
developement of bone, and may be observed 
by making a thin section of a bone at the point 
of junction of the bone and cartilage, where the 
shaft is connected with the epiphysis. (See 
Jig. 461.) The granular appearance will be 
Fig. 461. 
Transverse section of temporary cartilage in the first 
stage of ossification. 
a, a, intercellular tissue ossified; b, the trans- 
parent parietes of the enlarged corpuscle; c, the 
central nucleus, which in the specimen from which 
this figure was taken was granular. 
