koski1968 BAUME

Volume 54
Number 8
Cranial growth centers 571
Fig. 6. A photomicrograph of the basi-presphenoid synchondrosis of the rat showing the
resemblance of this cartilage to an epiphyseal growth plate.
Furthermore, the direction of growth of the maxilla may vary from 0 to 82 degrees
in relation to the sella-nasion lineI (Fig. 5). How would the sutures,
which are running in practically the same direction in every face, know when to
push the maxilla parallel to the reference line and when to push the jaw in an
almost straight downward direction ?
From the evidence presented, one comes to the conclusion that it is unlikely
that the sutural tissues have a tissue-separating force and that they are not,
therefore, even comparable to growth centers.
CRANIAL BASE SYNCHONDROSES
The importance of the synchondroses of the cranial base, especially of the
spheno-occipital synchondrosis, is stressed almost universally,4p ‘1 s* 71r 75, 78, Tsg *2*
a37 w 9o and most authors regard it as a growth center of primary value for the
growth of the craniofacial skeleton.
There is no doubt about the structural similarity between the basicranial
synchondroses and the epiphyseal growth plates, although some minor differences
in histology and histochemistry seem to exist between these two categories
of cartilage70 (Fig. 6). The reaction of the synchondroses to various biochemical
stimuli is also similar to that of the epiphyseal growth plates73 32s 69
and it is obvious that endochondral ossification is taking place adjacent to these
cartilages. The scene appears to be ready for the title of growth center-but
is it?
Actually, there appears to be no published evidence of the existence of a
tissue-separating force in the synchondroses. The removal of the spheno-occipital
synchondrosis has been observed to result in an arrest of growth in length of
the cranial base,lg but this does not prove that the cartilage has an independent
growth-promoting potential. The considerable amount of growth that occurs in