Bone & Cartilage Histology Flashcards
This is a semi-rigid tissue comprised of cell and ECM. The ECM contains collagen and elastic fibers and is typically surrounded by perichondrium.
Cartilage
These cells secrete cartilage matrix and have mitotic capabilities.
Chondroblasts
These are mature cartilage cells in lacunae. They are surrounded by matrix and form isogenous groups.
Chondrocytes
Cartilage lacks neurovasculature, so it receives nutrients from…
Diffusion via surrounding capillaries
T/F. Cartilage is very rigid and can easily be broken. It has a rough surface and cannot bear much stress.
False. Cartilage is flexible and resilient. It is smooth, lubricated and can bear mechanical stress without permanent distortion.
This type of tissue is ideal for mechanical and protective support.
Cartilage
ECM for cartilage is secreted by cells during development and for maintenance. The fiber types are…
Type II – predominant
Type I – may be present
Elastin – in elastic cartilage
What are the ground substances present in the ECM?
Hyaluronic acid
Chondroitin sulfate
***These are ground substances with proteoglycans
During chondrogenesis, differentiation takes place from the center and moves outward. Central cells are _______ and peripheral cells are ________.
Chondrocytes
Chondroblasts
What embryonic component does cartilage arise from?
Embryonic mesenchyme
What embryonic component does perichondrium arise from?
Superficial mesenchyme
Put the following steps of chondrogenesis in order:
A. ECM production traps cells in lacunae
B. Cells ‘round up’, divide, and are densely packed
C. Isogenous groups housed in lacunae
D. Cartilage arises from embryonic mesenchyme
- D
- B
- A
- C
***At the start they chondroblasts, by the end they are chondrocytes
This is a layer of dense irregular CT covering hyaline and elastic cartilage. It is not present in fibrocartilage and articular cartilage (subtype of hyaline cartilage). It is essential for growth and maintenance of cartilage.
Perichondrium
What is the outer/fibrous layer of Perichondrium made of?
Type I collagen
Fibroblasts
What is the inner/chondrogenic layer of Perichondrium made of?
Adjoins cartilage matrix
Contains mesenchymal stem cells
What layer of the Perichondrium is the source for new chondroblasts (divide/differentiate into chondrocytes)?
Inner/chondrogenic layer
This type of cartilage is homogeneous and semitransparent (in its fresh state). It is located in:
- Articular surfaces of synovial joints
- Large respiratory passages
- Costal cartilages
- Epiphyseal plates of long bones
- Portions of embryonic skeleton
Hyaline cartilage
In hyaline cartilage, the chondrocytes are located in lacunae and combine as _______ _______.
Isogenous groups
In hyaline cartilage, the chondrocytes secrete a matrix of _______ _______, which results in diffuse ________ staining.
Type II collagen
Basophilic
What are the types of cartilage?
Hyaline cartilage
Elastic cartilage
Fibrocartilage
In hyaline cartilage, this matrix immediately surround each chondrocyte and has the following characteristics:
- ECM consists of Type II collagen
- High GAGs
- Staining is more basophilic
Territorial matrix
In hyaline cartilage, this matrix surrounds the territorial matrix (surrounds isogenous groups) and has the following characteristics:
- ECM has more Type II collagen
- Fewer GAGs
- Staining is less basophilic
Interterritorial matrix
T/F. Elastic cartilage is the exact same as hyaline cartilage but with elastic fibers embedded in the ECM with Type II collagen.
True
What are elastic fibers useful for?
Recoil or rebound – allow for shape retention after deformation
Elastic cartilage is more flexible than hyaline cartilage, and is located where?
Auricle of ear
Walls of external auditory canals
Auditory (Eustachian) tubes
Epiglottis
This type of cartilage is formed from a mix of hyaline cartilage and dense CT, and lacks a perichondrium.
Fibrocartilage
Fibrocartilage is very tough, yet provides cushioning support tissue for bone. It is located in…
Intervertebral discs
Pubic symphysis
Meniscus
In this type of cartilage, chondrocytes are typically singly arranged in rows of isogenous groups. The matrix consists of sparse Type II collagen with fibroblasts and dense bundles of Type I collagen.
Fibrocartilage
Fibrocartilage matrix fibers are oriented in the direction of functional _______ and provides extra tensile strength.
Stress
This type of cartilage growth is done via mitotic division of preexisting chondrocytes in the lacunae. Secretion of new matrix separates daughter cells and increases mass of cartilage.
Interstitial growth
This type of cartilage growth is done when chondroblasts differentiate from progenitor cells in the perichondrium. They secrete Type II collagen and ground substance.
Appositional growth
Except in young children, damaged cartilage undergoes slow and incomplete repair. Why is this?
Due to its avascularity and low metabolic rate
In cartilage injury, cells of the _________ invade the injured area and produce new cartilage and/or dense CT. It may also be replaced with bone.
Perichondrium
Bone is a specialized CT that provides support and protection. It is comprised of ________ that are housed in lacunae.
Osteocytes
What is the matrix of bone made of?
Calcium phosphate as hydroxyapatite crystals
Type I Collagen
Proteoglycans
These are mesenchymal cells that produce osteoblasts, and are found in the periosteum and endosteum.
Osteoprogenitors
These cells produce and control osteoid, which is the non-mineralized organic matrix.
Osteoblasts
Some osteoblasts differentiate into ________, which are mature bone cells house in lacunae and maintain the bone matrix. Have long, spider-like processes.
Osteocytes
Osteocytes and osteoblasts communicate with each other to increase deposition of what?
Bone matrix
The are multi-nucleated cells that are formed via the fusion of monocytes. They exhibit a “ruffled border” which resorbs bone through H+ and lysosomal proteins.
Osteoclasts
________ and osteoblasts are typically located together, in developing bone.
Mesenchyme
This type of bone is solid and relatively dense. It makes up the external surfaces of long and flat bones. It is lamellar bone (mature bone).
Compact (cortical) bone
***Encompasses cancellous (spongy) bone
This type of bone contains trabeculae, which is an open lattice of narrow plates. It makes up the internal layer of bone and is porous to house bone marrow. It can be lamellar (mature) or woven (immature) bone.
Cancellous (spongy) bone
This type of bone is considered immature or primary, and is usually replaced by mature bone. It is characterized by a loose arrangement of collagen fibers and has a low mineral content with more cells.
Woven bone
***Forms during fracture repair and remodeling
This is a component of long bone that are knobby regions at the ends. Compact bone is superficial with spongy bone deep. Contains the epiphyseal plate.
Epiphysis
This is the elongated shaft of long bone.
Diaphysis
This is the component of long bone that is between the diaphysis and epiphysis and consists of spongy bone.
Metaphysis
This lies within the metaphysis and is formed when the epiphyseal plate has fused.
Epiphyseal line
This is the cylindrical space in the diaphysis contains bone marrow.
Marrow cavity
This bone covering is made of dense irregular CT and covers the external surface. It does NOT cover articular cartilages.
Periosteum
Periosteum is neuromuscular, anchored by ________ ________ embedded in the bone matrix, and contains ________.
Perforating fibers
Osteoblasts
This bone covering is made of CT and lines all trabeculae and marrow cavity.
Endosteum
The endosteum contains _________ cells, reticular cells of bone marrow, and CT fibers.
Osteoprogenitor
This is a cylindrical, layered structure comprised of mature bone. It runs parallel to the diaphysis.
Osteon
The osteon consists of concentric _________ bone matrix that surrounds a _______ _______ that carries blood vessels and nerves.
Lamellae Central canal (Haversian canal)
This is lamellae that lie in between osteons. It is composed of remnants of previous concentric lamellae.
Interstitial lamellae
This type of lamellae lines the entire inner and outer circumferences of the diaphysis.
Circumferential lamellae (Inner and Outer)
These are channels used by vasculature to travel from periosteal and endosteal surfaces to the central canal (Haversian canal).
Perforating canals
These are tiny channels between lacunae that allow interactions between osteocytes.
Canaliculi
Spongy bone tissue is most easily seen in bones of the ________ and are oriented in position that maximize strength while minimizing mass.
Skull
Spongy bone tissue is arranged as _________, which is an open lattice of narrow lamellar plates. Houses bone marrow.
Trabeculae
In this type of ossification, the preexisting hyaline cartilage is eroded and invaded by osteoblasts which will begin osteoid production.
Endochondral ossification
In this type of ossification, osteoblasts differentiate directly from mesenchyme and begin secreting osteoid.
Intramembranous ossification
Where does endochondral ossification usually occur?
Bones of extremities
Pectoral and pelvic girdles
Vertebrae
Ends of clavicles
Where does intramembranous ossification usually occur?
Flat bones of skull
Most facial bones (mandible)
Central part of clavicle
In both endochondral ossification and intramembranous ossification, (WOVEN/LAMELLAR) bone is produced first and is replaced by (WOVEN/LAMELLAR) bone.
Woven
Lamellar
T/F. During bone growth, only woven or lamellar bone can exist in one area.
False. Areas of woven bone, bone resorption, and lamellar bone all exist together.
Put the following steps of endochondral ossification in order:
A. Cartilage calcifies, and a periosteal bone collar forms around diaphysis.
B. Secondary ossification centers form in epiphyses.
C. Fetal hyaline cartilage model develops.
D. Bone replaces cartilage, except the articular cartilage and epiphyseal plates.
E. Primary ossification center forms in the diaphysis.
F. Epiphyseal plates ossify and form epiphyseal lines.
- C
- A
- E
- B
- D
- F
During the growth of endochondral bone, there are zones of cartilage at each end of the diaphysis of long bones. What are the zones, going from diaphysis to epiphysis?
Zone of ossification/resorption Zone of calcified cartilage Zone of hypertrophy Zone of proliferation Zone of reserve cartilage
This zone of cartilage has no active matrix and is closest to the epiphysis.
Zone of reserve cartilage
This zone of cartilage is where cartilage cells undergo division and organize into distinct columns. They actively produce collagen (types II and XI) and other matrix proteins.
Zone of proliferation
This zone of cartilage is where chondrocytes are greatly enlarged. There is clear cytoplasm, and they secrete factors that initiate vascular invasion.
Zone of hypertrophy
This zone of cartilage is where hypertrophied cells begin to degenerate and cartilage matrix becomes calcified. It serves as the initial scaffold for deposition of new bone.
Zone of calcified cartilage
This zone of cartilage is nearest the diaphysis. It is where calcified cartilage is in direct contact with marrow cavity. Blood vessels and osteoprogenitors invade the region and the osteoprogentior cells will differentiate into osteoblasts.
Zone of ossification/resorption
This is an autosomal dominant syndrome that occurs due to a mutation in FGFR3. In endochondral growth, there is decreased chondrocyte proliferation at the epiphyseal plate due to the FGFR3 signaling being gone. This causes bones to not lengthen.
Achondroplasia (most common form of dwarfism)
What are some symptoms of Achondroplasia?
Small mid face (defects in cranial base)
Altered spinal curvature
In this type of bone growth, there is growth in circumference (width) of long bones via osteoblasts in the periosteum.
Appositional bone growth
Appositional bone growth begins with the formation of the _______ _______ on the cartilaginous diaphysis and is accompanied by the enlargement of the marrow cavity by ________ in the endosteum.
Bone collar
Osteoclasts
This disease can be caused by a calcium deficiency in children. The bone matrix does not calcify normally and the epiphyseal plate can become distorted by the normal strains of body weight and muscular activity.
Rickets
In Rickets disease, the ossification processes are impeded, which causes bones to grow more slowly and often become deformed. The deficiency can be due either to insufficient ________ in the diet or a failure to produce the steroid pro hormone _________, which is important for the absorptions of calcium by cells of the small intestine.
Calcium
Vitamin D
This is caused by deficient calcification of recently formed bone and partial decalcification of already calcified matrix. This is due to dietary vitamin D deficiency, lack of sun exposure, and GI disease. Can be asymptomatic.
Osteomalacia
Rickets is also known as ________ ________.
Juvenile Osteomalacia
In Rickets (Juvenile Osteomalacia) there is a vitamin D deficiency, and decreased absorption of calcium and ________ from the bowels.
Phosphorus
What are signs of Rickets?
Delayed closure of fontanelles Parietal and frontal bossing (bone sticks out) Craniotabes (soft skull bones) Bowed arms and legs Wide wrists
Old osteons are reabsorbed by _________, creating tunnels. Osteoprogenitors then invade these tunnels and form ________ which secrete osteoid. A new osteon forms with concentric lamellae and trapped _________. Interstitial lamellae remain.
Osteoclasts
Osteoblasts
Osteocytes
In healthy adults, how much bone turns over annually?
5-10 percent
Put the following steps of bone fracture repair in order:
A. A fibrocartilaginous (soft) callus forms
B. The bone is remodeled
C. A fracture hematoma forms
D. A hard (bony) callus forms
- C
- A
- D
- B
Torn blood vessels within a fracture release blood, which clots and forms a…
Fracture hematoma
A fracture hematoma is removed by macrophages and replaced by a fibrocartilage-like mass called a…
Soft callus
If a soft callus is torn, the _______ reestablishes continuity over it.
Periosteum
The soft callus is invaded by blood vessels and osteoblasts, then fibrocartilage is gradually replaced by woven bone and forms a…
Hard callus
The hard callus (woven bone) is remodeled as _______ and _______ bone, and vasculature is reestablished.
Compact
Cancellous
This is a disease caused by a decrease in bone mass and increased fragility. Patient loses the ability to produce organic matrix (mainly collagen), and loses calcium and other bone salts.
Osteoporosis
Osteoporosis is common in who?
Elderly and post-menopausal women
***No clinical manifestations until there is a fracture
Synovial Joints contain this type cartilage, which reduces friction, is avascular, and is nourished by synovial fluid.
Articular cartilage
***Remember, it’s a type of hyaline cartilage but lacks a perichondrium
This type of cartilage is found on the surfaces of movable joints (2-5 mm thick). It is composed or remnants of original hyaline cartilage templates used by the developing bone.
Articular cartilage
Articular cartilage has collagen fibers that run perpendicular to the tissue surface, but bend gradually to form an arc. This establishes four zones, which are…
Superficial zone
Intermediate zone
Deep zone
Calcified zone
This zone of articular cartilage has elongated and flattened chondrocytes.
Superficial zone
This zone of articular cartilage has round chondrocytes.
Intermediate zone
This zone of articular cartilage has chondrocytes arranged in short columns.
Deep zone
This is what separates the calcified zone and deep zone of articular cartilage.
Tidemark
This zone of articular cartilage has small chondrocytes surrounded by calcified matrix. The borders are subchondral bone.
Calcified zone
This is a degenerative joint disease related to aging and injury of articular cartilage. It is characterized by chronic joint pain and various degrees of joint deformity and destruction of the articular cartilage.
Osteoarthritis
What types of joints does osteoarthritis commonly affect?
Weight-bearing joints
At the early stages of osteoarthritis, the superficial layer of the _______ _______ is disrupted.
Articular cartilage
In the late stages of osteoarthritis, the destruction of the articular cartilage extends to the bone, where the exposed _________ bone becomes a new articular surface. This causes a progressive reduction in mobility and increased pain.
Subchondral
