Biomedical Engineering Reference
In-Depth Information
Lacunae
This quasi-circular arc
is part of the cellular
interface (IC)
Canaliculi
Space for a
blood vessel
or nerve
Cement line
Osteonal canal
The surfaces of the lacunae
and the canaliculi form the
lacunar - canalicular interface
(ILC)
The collagen - apatite
porosity exists in the domains
outside of the vascular and
lacunar - canalicular porosities (PV and PLC)
Figure 9.7
A transverse cross section of a
pie-shaped section of an osteon. The os-
teonal canal is on the upper right, and the
cement line is to the left. The osteonal
canal is part of the vascular porosity, the
lacunae and the canaliculi are part of the
lacunar-canalicular porosity, and the ma-
terial in the space that is neither vascular
porosity nor lacunar-canalicular porosity
contains the collagen-apatite porosity. The
three interfaces, the cement line, the cellular
interface, and the lacunar-canalicular inter-
face, are indicated separately. The radius of
an osteon is usually about 100-150mm, and
the long axis of a lacuna is about 15mm.
Using this information, it should be possi-
ble to establish the approximate scale of the
printed version of this illustration.
molecules, such as albumin (mol wt 68 000) and horseradish peroxidase (mol wt
40 000), have been shown to leak out of bone capillaries into the interstitial fluid
[37, 38], and they must have a pathway to return to the general circulation. Kolodny
[39] demonstrated that 2 weeks after India ink was injected into the medullary
cavity of long bones, carbon particles were found in the regional lymph nodes.
However, attempts to demonstrate discrete lymphatic vessels within the marrow
and bone tissue have been consistently unsuccessful. It has been shown with
injection studies using thorotrast [40] that this substance leaks from the capillaries
of cortical bone into the perivascular fluid and that eventually it can be seen
in the periosteal lymphatic vessels. A similar finding has been observed in the
cortical bone after the use of India ink [9]. The indirect conclusion seems to be
that, although there are no demonstrable lymphatic channels in bone tissue, the
perivascular fluid as a whole circulates toward the periphery of the bone, carrying
with it substances such as large proteins and carbon particles to be taken up by a
mechanism at or near the periosteum.
