Download CT 2 filled

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HYALINE CARTILAGE TISSUE
General:
•Gel GS; flexible solid,
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Skeletal tissue; support
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Rigidity unnecessary
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Ground substance (GS)
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Chondroitin sulfate
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Fibers embedded in GS
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Usually collagen (type II)
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Chondrocytes: mature cartilage cells;
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inactive; in lacuna (“tiny lake”);
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Cell shriveled.
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Cartilage; avascular; not innervated.
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heals slowly
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Often surrounded by a
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Perichondrium
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dense irregular CT layer
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HYALINE CARTILAGE TISSUE
• Specific characteristics
• Matrix; abundant, indistinct
collagen fibers.
• Two reasons:
• collagen fibers and
the ground
substance
• same refractive
index
• GS unstained with
eosinophilic dyes
• Matrix looks afibrous;
• Slightly smokey
glass.
• Hyaline = glassy.
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HYALINE CARTILAGE TISSUE
• Chondrocytes are clumped
• Chondroblasts are mitotic:
• divide once or twice
• cells stay together.
• 2-5 chondrocytes
• Matrix unevenly basophilic, near clumps.
• Ground substance is chondroitin
sulfate,
• Glycosaminoglycan: an un-
branched, sulfated, polysaccharide
• produced by the chondroblasts
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HYALINE CARTILAGE TISSUE
• Hyaline cartilage, most common
• Nasal cartilages ; most of larynx
• Trachea and bronchi
• Cartilage models ; precursors to
bones
• Articular cartilage; modified hyaline
cartilage
• Ends of bones,
• Slightly soft, slippery layer
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for articulation.
Resembles regular hyaline
cartilage except:
• Evenly scattered single
chondrocytes.
• Uniform basophilic stain.
• Hyaline cartilage; matrix about 80% of
tissue volume.
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ELASTIC CARTILAGE
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Elastic cartilage, next-mostcommon
• Ear and epiglottis.
Predominantly elastic fibers.
Visible even without staining.
H&E staining, matrix is lightly
eosinophilic,
• Due to collagen fibers
• Special staining for elastic
fibers.
Chondrocytes are evenly
distributed
• Most of the tissue’s volume
• Larger than those of
hyaline cartilage.
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Fibrocartilage
• Third type of cartilage
• Lots of collagen fibers.
• Very tough
• Intervertebral discs
• Pubic symphysis.
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j. COMPACT BONE (dense bone)
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Filippo Brunelleschi
Dome of the Florence Cathedral
Early 15th century
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COMPACT BONE (dense bone)
General characteristics of bone:
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Ground substance; rigid solid
• Bone; skeletal tissue
• structural support.
• GS; inorganic crystalline solid
• calcium phosphate and
calcium carbonate
• hydroxyapatite or
hydroxycalcium
phosphate.
• Other ions; carbonate,
magnesium, sulfate, and
fluoride.
• GS : half of the matrix.
• GS unstained with H&E.
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COMPACT BONE (dense bone)
• Half matrix is collagen fibers
• Bundles of parallel fibers.
• Matrix formation
• Collagen fibers form
first
• GS crystals deposited
on collagen fibers
• Crystals then enlarge, fill
in remaining matrix
space.
• Collagen fibers eosinophilic,
matrix bright red with H&E.
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COMPACT BONE (dense bone)
• Parallel collagen bundles
• give the matrix strength.
• Crystalline solid + protein fibers
analogous to:
• Concrete and steel rods of
foundations of buildings
• Fibers or rods reduce the
brittleness of the ground
substance
• GS gives the matrix rigidity.
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COMPACT BONE (dense bone)
• Bone cells; osteocytes
• metabolically active
• numerous thin branching cell
extensions
• extend through matrix
• interconnect with other
osteocytes.
• Cell extensions within channels
called canaliculi
• "tiny canals”: singular:
canaliculus
• Extensions form and
interconnect before the
matrix is well developed.
canaliculi
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Three osteocytes
COMPACT BONE (dense bone)
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Osteocytes; not active in bone formation
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Osteoblasts, immature bone cells,
produce matrix,
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Osteoblasts become the
osteocytes.
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Osteoblasts are stimulated by Vitamin D
• hormone thyrocalcitonin or
calcitonin (thyroid)
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Osteoblasts development
• mesenchymocyte >>
osteoprogenitor cell>> osteoblasts
>> osteocyte
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Osteoblasts become osteocytes when
trapped in the matrix
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Body (soma) of each osteocyte is
in a lacuna.
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COMPACT BONE (dense bone)
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Bone more dynamic than cartilage
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Youth, bone remodeling common
• undergoing matrix
deposition and erosion
• Slows with age.
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Osteoclasts ; bone matrix
erosion.
• large, multinucleate cells
• eosinophilic cytoplasm
• pH change erodes bone
matrix
• GS dissolves
• stimulated by parathyroid
hormone
• frees Ca2+ from the matrix.
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COMPACT BONE (dense bone)
• Bone matrix is in layers;
lamellae (lamella; singular) .
• Lamellae are of similar
thickness and lie against
each other.
• Each lamella: bundles of
collagen fibers are
parallel to each other
• adjacent lamellae ;
fibers in a different
direction
• Contributes to the
overall strength of
the tissue.
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COMPACT BONE (dense bone)
• Surrounding the developing
bone is layer of immature
bone tissue--periosteum
• Periosteum similar to
perichondrium
• remains after growth
of bone tissue
• an inactive layer.
http://neuromedia.neurobio.ucla.edu/campbell/bone/wp.htm
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