koski1968 BAUME

Volume 54
Number 8
Cranial growth centers 5 69
Fig. 3. A photomicrograph of a section of the intern-1 suture of the rat. Note that the
periosteum appears to be continuous all around the bone edges, with a vascular layer between
the periosteal layers in the suture itself.
“the apposition of new bone at the sutural surfaces enlarges the single bones
but not the cranium.“s3 This concept is challenged by others, who maintain that
the sutures are not acting as primary growth agents56-5sy 75~ 77 but that the growth
in the sutural areas is secondary and caused by the growth of cartilaginous elements
of the craniofacial complex75y 77 or by the effect of the so-called “functional
matrix.“56l 58
Obviously, these differing opinions are not necessarily correlated with the
different views of the functional structure of the sutures. Whether the appositional
growth at the bone edges in the sutural areas is regarded as being due
primarily to the proliferation of the middle layer cells or of the cambial layer
cells, it may still be either a relatively independent growth process or governed
by some external forces.
Evidence in favor of the dependent role of the sutural growth appears to
be accumulating.
The literature contains only a few observations that are directly related to
this problem. It has been observed that the trabecular pattern in the bones at
the sutures changes with age, probably indicating the changes in the direction
of growth,34 and it is difficult to believe that the sutural tissue itself would have
the information necessary for altering the direction of growth. Subcutaneous
autotransplants of the zygomaticomaxillary suture area in the guinea pig have