Specialized Connective
Tissues: Bone and
Cartilage
Questions
DIRECTIONS: Each item below contains a question or incomplete
statement followed by suggested responses. Select the one bestresponse to
each question.104.Intramembranous ossification differs from endochondral ossification
in which of the following ways?
a. Action of osteoblasts
b. Light microscopic appearance of the adult bone
c. Ultrastructural appearance of the adult bone
d. Presence of woven bone early in the ossification process
e. Microenvironment in which ossification occurs105.A 7-year-old boy is referred to the endocrine clinic with short stature,
rhizomelic shortening of the arms and legs, a disproportionately long trunk,
trident hands, midfacial hypoplasia, prominent forehead (frontal bossing),
thoracolumbar gibbus, and megalencephaly. Radiological examination by
MRI reveals caudal narrowing of the interpedicular spaces of T1 and T2 ver-
tebrae and spinal stenosis at L2–L4. Genetic analysis reveals a gain of function
mutation, G1138A, in the fibroblast growth factor receptor-3 (FGFR3),band
4p16.3. His parents are requesting the initiation of treatment with growth
hormone. The endocrinologist is concerned about harmful growth hormone
effects: deposition of abnormally-formed bone and worsening of the patient’s
kyphoscoliosis. During this child’s postnatal development, which of the fol-
lowing is the most likely effect of the FGFR-3 gene mutation?
a. Decreased bone deposition under the periosteum
b. Decreased proliferation of osteoblasts in the primary ossification center
c. Decreased proliferation of osteoblasts in the secondary ossification center
d. Decreased appositional growth of chondroblasts in the primary ossification center
e. Decreased interstitial growth of chondroblasts in the epiphyses193Copyright © 2007 by The McGraw-Hill Companies, Inc. Click here for terms of use.