Biology Reference
In-Depth Information
DA
bone
osteoclast
osteoclast
Fig. 8.6 Osteoclasts in a bone biopsy obtained from a patient suffering from pycnodysostosis.
Note the demineralized area (DA) adjacent to the ruffled border of the two osteoclasts [From
Everts et al. (
1985
).]
a
b
blc
osteoclast
osteoclast
DA
RB
bone
bone
DA
Ocy
Fig. 8.7 Mouse bone explants were cultured for 6 h in the presence of a selective inhibitor of
cysteine proteinases and during this period the osteoclast demineralizes the bone but degradation
of the matrix is blocked. Microscopic examination shows huge areas of demineralized bone matrix
(DA) adjacent to the osteoclast. (a) Light micrograph of a section stained with the trichrome
Goldner's stain. The
green areas
denote bone and the
orange
stained area is demineralized bone.
(b) Electron micrograph of a comparable area.
Blc
bone lining cell,
Ocy
osteocyte,
RB
ruffled
border,
DA
demineralized area
osteopetrosis, and adjacent to the osteoclasts areas of demineralized non-digested
bone matrix were readily found (Fig.
8.8
; (Saftig et al.
1998
; Gowen et al.
1999
),
thus mimicking pycnodysostosis. Gelb et al. (
1996
) and Johnson et al. (
1996
)
demonstrated that patients suffering from pycnodysostosis had a defect in the
gene responsible for the expression of cathepsin K, as a consequence these patients
lacked active cathepsin K. Finally, selective inhibitors and interference with the
