Download Connective Tissue4_Cartilage and Bone

10.0 CONNECTIVE TISSUE: CARTILAGE AND BONE
Upon completion of this lecture, students will be able to:
a) Define and use properly the following words: Cartilage, Perichondrium, Matrix,
Pericellular matrix, Territorial matrix, Lacunae, Avascular, Chondroblast , Chondrocyte,
Chondroclast, Hyaline Cartilage, Growth Plate, Synchondroses, Articular cartilage,
Elastic Cartilage, Van Giesen's stain, Fibrous Cartilage, String of pearls, Bone,
Osteoblast, Trabeculae, Osteoid, Osteocyte, Osteoclast, Multinucleated giant cell,
Collagen Type I, Hydroxyapatite crystals, Woven bone, Lamellar Bone, Compact bone,
Osteons, Central canal, Canaliculi, Perforating canal (Volkmann's canal), Periosteum,
Endosteum, Spongy bone, Cancellous bone.
b) Describe and associate basic structure/function for the following: 1) all structures listed
above; 2) nutrition for cartilage.
c) Identify by microscopy: Articular cartilage, bone marrow, Canaliculi, Cancellous bone,
Central canal, chondroblasts, chondroclast, Chondrocyte, Compact bone, Elastic
Cartilage, Endosteum, Fibrous Cartilage, Growth Plate, Hyaline Cartilage, Lacunae,
lamellae, Lamellar Bone, matrix, Multinucleated giant cell, Osteoblast, osteoclast,
Osteocyte, osteoid, Osteons, Perforating canal, Pericellular matrix, perichondrium,
Periosteum, Spongy bone, string of pearls, Territorial matrix, trabeculae.
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CONNECTIVE TISSUE: CARTILAGE AND BONE
I.
CARTILAGE
A. GENERAL CHARACTERISTICS OF CARTILAGE
1. Perichondrium
a. fibrous outside layer; dense CT with chondroblasts (not in articular
cartilage)
b. cellular inside layer contains differentiated chondroblasts
2. Matrix
a. Pericellular matrix (very dark due to sulfated proteoglycans)
b. Territorial matrix (near the chondrocytes)
i. darker staining; basophilia due to sulphur groups and acidic
groups
c. Interterritorial matrix stains less intensely
3. Lacunae
a. An artifact of fixation leaves spaces where chondrocytes reside
4. Avascular
a. nutrients must diffuse into cartilage
B. CELLS OF CARTILAGE
1. Chondroblast
a. Cartilage forming cells (found in aggregates or clusters after mitosis)
b. produces matrix
i. Type II collagen
ii. proteoglycans (chondroitin sulfate)
c. blast cells found in growing cartilage (as part of the skeleton)
2. Chondrocyte is the resting stage (similar to the fibrocyte)
3. Chondroclast
a. Multinucleated cell (Monocytic line); similar to a large macrophage
b. resorption of cartilage to provide for remodeling of the skeletal tissues
C. TYPES OF CARTILAGE
1. Hyaline Cartilage
a. The most common cartilage
b. The Growth Plate (elongation of bone) is the area of stimulated growth
c. Joints (Synchondroses)
d. Matrix of hyaline cartilage consists of:
i. collagen type II
ii. Proteoglycans, particularly chondroitin sulfate
2. Articular cartilage
a. specialized hyaline cartilage
3. Elastic Cartilage
a. contains elastin fibers more than collagen
b. Stains with Orcein and Van Giesen's
c. found in the pinna of the ear, epiglottis, larynx and few other places.
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4. Fibrous Cartilage
a. Dense connective tissue
b. Intervertebral disc and menisci (also associated with dense CT in
ligaments)
c. Chondrocytes are located in straight lines
d. Appearance can vary with location & age
e. vertebral column = "string of pearls"
f. Meniscus of knee joint = "herringbone pattern"
g. Fibrous can also be found in articular cartilage
II.
BONE
A. CELLS OF BONE
1. Osteoblast
a. Bone forming cells
b. located at matrix periphery (edge of trabeculae)
c. secretes osteoid (bone matrix; an organic extracellular substance; large
amounts of tropocollagen)
d. derived from mesenchymal cell
2. Osteocyte is the resting cell (renews matrix) that becomes trapped within its own
matrix
3. Osteoclast
a. Multinucleated giant cell
b. sits in the resorbing canal and on the surface of trabeculae
c. has a Ruffled border and contains vacuoles
d. derived from monocyte/phagocyte line
e. resorbs bone matrix when calcium is needed
f. stimulated in response to the hormone, parathormone
B. BONE MATRIX
1. Collagen Type I is the fiber type (90%)
2. Non-collagen proteins such as glycoproteins initiate the mineralization
3. Hydroxyapatite crystals (hold calcium) and form the mineral component
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C. TYPES OF BONE
1. Woven bone
a. Immature form that has random weaves of collagen fibers and ground
substance
b. Remodeled to form lamellar bone
2. Lamellar Bone
a. Compact bone (calcified)
i. hard dense outer regions of the diaphysis and epiphysis
ii. Osteons are formed by the parallel bony columns of concentric
iii. Central canal (center of osteon; blood vessels, nerve)
iv. canals (canaliculi) for communication between osteocytes
v. Perforating canal (Volkmann's canal) carry blood vessels
vi. Periosteum (CT external surface covering containing fibers and
cells)
vii. Endosteum consists of loose CT lining of osteonal canals and the
space between compact bone and bone marrow
b. Spongy bone
i. also called Cancellous bone
ii. dimensional trabeculae or spicules
iii. caverns (spaces or pores) of loose connective tissue and blood
vessels
iv. Surrounds bone marrow in the medullary cavity which produces
blood cells
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