Br Histology: Cartilage And Bone

Front 1

What is the most abundant collagen? Which collagen serves as temporary skeleton until replaced by bone?

Back 1

Hyaline

Front 2

What type of collagen is in hyaline cartilage? How are condrocytes arranged? Is there a perichondrium?

Back 2

1) Type II
2) arranged in groups (isogenous groups)
3) perichondrium everywhere except articular surfaces

Front 3

Where are several locations of hyaline cartilage?

Back 3

1) articular ends of long bones
2) nose
3) larynx
4) trachea
5) bronchi
6) ventral ends of ribs
7) template for endochondral bone formation

Front 4

What type of collagen is in elastic cartilage?

Back 4

1) type II with elastic fibers
2) pinna of ear
3) auditory canal and tube
4) epiglottis
5) some laryngeal cartilages

Front 5

What type of collagen is in fibrocartilage? What are characteristics of matrix? How are chondrocytes arranged? What is it always associated with?

Back 5

1) Type I
2) acidophilic
matrix
3) chondrocytes
arranged in
parallel rows between
bundles of collagen
4) always associated with
dense collagenous connective
tissue and/or
hyaline cartilage

Front 6

Where is fibrocartilage found?

Back 6

1) Intervertebral discs
2) articular discs
3) pubic symphysis
4) insertion of tendons
5) meniscus
of knee

Front 7

What does the perichondrium consist of? What is its function?

Back 7

(1) consists of an outer fibrous layer, containing type I collagen,
fibroblasts, and blood vessels, and an inner cellular layer,
containing chondrogenic cells and chondroblasts.
(2) It provides the nearest blood supply to the avascular cartilaginous
tissue

Front 8

What cellular components do chondroblasts contain?

Back 8

1) cells contain:
a. an extensive Golgi complex
b. abundant rough endoplasmic reticulum
c. lipid droplets
d. glycogen.

Front 9

Where do chondrocytes arise from/

Back 9

1) They arise by differentiation of mesenchymal chondrogenic
cells and from chondrogenic cells located within the inner layer of the perichondrium into chondroblasts, which are the earliest cells to produce cartilage matrix
2) Once these cells become totally enveloped by matrix, they are referred to as chondrocytes

Front 10

which hormones stimulate cartilage?

Back 10

1) Thyroxine
2) testosterone
3) somatotrophin

Front 11

Which hormones inhibit cartilage formation?

Back 11

1) Cortisone
2) hydrocortisone
3) estradiol

Front 12

How does hypovitaminosis A affect cartilage? Hypervitaminosis?

Back 12

1) hypo = Diminishes thickness of epiphyseal plates
2) hyper = Accelerates ossification of epiphyseal plates

Front 13

How does hypovitaminosis C affect cartilage?

Back 13

1) Stops matrix production
2) distorts cartilage columns in epiphyseal plates
3) scurvy develops.

Front 14

How does hypovitaminosis D affect cartilage?

Back 14

1) Epiphyseal cartilage cells proliferate, but matrix fails to calcify
2) growing bones become deformed
3) rickets develops

Front 15

What cells give rise to interstitial hyaline cartilage growth? When does it occur in life?

Back 15

1) results from cell division of preexisting chondrocytes
2) This type of growth occurs only during the early stages of cartilage formation and in articular cartilage and the epiphyseal plates of long bones.

Front 16

appositional hyaline cartilage growth results from what? What type of growth is it?

Back 16

1) results from differentiation of chondrogenic cells in the perichondrium
2) This type of growth results in the formation of chondroblasts and/or new chondrocytes, which elaborate a new layer of cartilage matrix at the periphery

Front 17

How does elastic cartilage differ from hyaline cartilage?

Back 17

1) all elastic cartilage has perichondrium
2) elastic fibers impart a yellow color
3) same type II collagen

Front 18

How does fibrocartilage differ from hyaline cartilage?

Back 18

1) lacks identifiable perichondrium
2) has alternating rows of chondrocytes and not arranged in groups
3) type I collagen instead of type II

Front 19

Under what conditions can osteoprogenitor cells become chondrogenic cells?

Back 19

at low oxygen tensions, they may change into chondrogenic cells.

Front 20

How do osteoblasts stain and appear?

Back 20

On bony surfaces, they resemble a layer of cuboidal, basophilic cells
as they secrete organic matrix

Front 21

How do osteocytes communicate with one another?

Back 21

gap junctions

Front 22

what are cytologic features of osteocytes?

Back 22

1) abundant heterochromatin
2) a paucity of RER
3) small Golgi complex

Front 23

What are some histologic and features of osteoclasts?

Back 23

1) Osteoclasts are large, motile, multinucleated cells (up to
50 nuclei)
2) Their cytoplasm is usually acidophilic

Front 24

What are howships lacunae?

Back 24

1) osteoclasts form
2) they are located in depressions
which represent areas of bone resorption

Front 25

What are the morphologic zones seen with an electron micrograph when looking at an osteoclast?

Back 25

(1) The ruffled border is the site of active bone resorption
a. It is composed of irregular finger-like cytoplasmic projections extending
into Howship lacunae.
(2) The clear zone surrounds the ruffled border
a. It contains microfilaments,
which help osteoclasts maintain contact with the bony
surface, and serves to isolate the region of osteolytic activity.
(3) The vesicular zone contains exocytotic vesicles that transfer
lysosomal enzymes to Howship lacunae and endocytotic vesicles
that transfer degraded bone products from Howship lacunae to
the interior of the cell.
(4) The basal zone is located on the side of the cell opposite the ruffled
border.
a. It contains most of the cell organelles.

Front 26

What are the event of bone resorption?

Back 26

(1) Osteoclasts secrete acid, thus creating an acidic environment that decalcifies the surface layer of bone.
(2) Acid hydrolases, collagenases, and other proteolytic enzymes secreted
by osteoclasts then degrade the organic portion of the
bone.

Front 27

What is another name for spongy bone? What is it composed of?

Back 27

1) cancellous bone,
2) composed of interconnected
trabeculae
3) Trabeculae surround cavities filled with bone marrow
4) The trabeculae contain osteocytes and are lined by a single layer of osteoblasts

Front 28

What are features of primary or woven bone? does it have high or low mineral content? when is it found?

Back 28

(1) Primary bone contains many osteocytes and large, irregularly arranged type I collagen bundles.
(2) It has a low mineral content.
(3) It is the first compact bone produced during fetal development and
bone repair.
(4) It is remodeled and replaced by secondary bone except in a few places (e.g., tooth sockets, near suture lines in skull bones, and
at insertion sites of tendons).

Front 29

What are features of secondary or lamellar bone?

Back 29

(1) Secondary bone is the compact bone of adults.
(2) It has a calcified matrix arranged in regular layers, or
lamellae.
(3) Each lamella is 3-7 micrometers (um) thick.
(4) It contains osteocytes in lacunae, which are located between, and occasionally within, lamellae

Front 30

What are Haversian systems?

Back 30

1) osteons
2) long cylinders that run approximately parallel to the long axis of the diaphysis.

Front 31

What does a haversian canal contain?

Back 31

1) blood vessels
2) nerves
3) and loose connective tissue.

Front 32

How are haversian canals connected?

Back 32

1) They are interconnected by Volkmann canals, which also connect to the periosteum and endosteum and carry the neurovascular supply.

Front 33

What are interstitial lamellae?

Back 33

1) irregularly shaped lamellae located between haversian systems
2) They are remnants of remodeled haversian systems.

Front 34

Which bones undergo intramembraneous bone formation?

Back 34

flat bones (e.g., parietal bones of the skull) are formed.

Front 35

The primary center of ossification develops at the midriff of the
diaphysis of the hyaline cartilage model. What are the following events?

Back 35

(1) Vascularization of the perichondrium at this site causes the transformation of chondrogenic cells to osteoprogenitor cells,
which differentiate into osteoblasts
a. This region of the perichondrium is now called the periosteum.
(2) Osteoblasts elaborate matrix deep to the periosteum, and via intramembranous
bone formation, form the subperiosteal bone collar.
(3) Chondrocytes within the core of the cartilaginous model undergo hypertrophy and degenerate, and their lacunae become confluent, forming large cavities (eventual marrow spaces).
(4) Osteoclasts create perforations in the bone collar that permit the periosteal bud (blood vessels, osteoprogenitor cells, and mesenchymal
cells) to enter the newly formed spaces in the cartilaginous
model. The cartilage that constitutes the walls of these
spaces then becomes calcified.
(5) Newly developed osteoblasts elaborate bone matrix that becomes
calcified on the surface of the calcified cartilage, forming a calcified cartilage-calcified bone complex. In histologic sections the calcified cartilage stains basophilic, whereas the calcified bone stains acidophilic.
(6) The subperiosteal bone collar becomes thicker and elongates toward the epiphysis.
(7) Osteoclasts begin to resorb the calcified cartilage-calcified bone complex, thus enlarging the primitive marrow cavity.
(8) Repetition of this sequence of events results in bone formation spreading toward the epiphyses

Front 36

Secondary centers of ossification develop at the epiphyses in a
sequence of events similar to that described for the primary center, except
a bone collar is not formed. What is process?

Back 36

(1) Development of these centers begins when osteoprogenitor cells
invade the epiphysis and differentiate into osteoblasts, which elaborate bone matrix to replace the disintegrating cartilage. When the epiphyses are filled with bone tissue, cartilage remains in two areas, the articular surfaces and the epiphyseal plates.
(2) Articular cartilage persists and does not contribute to bone formation.
(3) Epiphyseal plates continue to grow by adding new cartilage at the epiphyseal end while it is being replaced at the diaphyseal end (lengthening the bone).
(4) Ossification of the epiphyseal plates and cessation of growth
occurs at about age 20.

Front 37

The Zones of the epiphyseal plates are histologically distinctive and arranged how? What are features of each?

Back 37

1) zone of reserve = cartilage near epiphyseal side of plate with randomly arranged inactive chondrocytes
2) zone of proliferation = rapid mitotic division forming isogenous cell groups
3) zone of hypertrophy and maturation = chondrocytes are greatly enlarged
4) zone of calcification = hypertrophied chondrocytes die and cartilage ossifies
5) zone of ossification = newly formed osteoblasts form bone matrix

Front 38

How does calcification begin?

Back 38

with the deposition of calcium phosphate on collagen fibrils and is stimulated by certain proteoglycans and osteonectin,
a Ca2+-binding glycoprotein

Front 39

Where does the proliferation of osteoprogenitor cells begin when there is a fracture?

Back 39

in the periosteum and
endosteum in the vicinity of the fracture.

Front 40

Describe the process of a bony callus?

Back 40

a. Fibrous connective tissue and hyaline cartilage are formed in the fracture zone.
b. Endochondral bone formation replaces the cartilage with primary bone.
c. Intramembranous bone formation also produces primary bone in the area.
d. The irregularly arranged trabeculae of primary bone join the ends of the fractured bone, forming a bony callus
e. The primary bone is resorbed and replaced with secondary bone as the fracture heals

Front 41

Describe vitamin A and its effect on bone? Does a deficiency or excess result in small bone growth?

Back 41

1) deficiency inhibits proper bone formation and growth
2) an excess accelerates ossification of the epiphyseal plates.
3) Deficiency
or excess results in small stature.

Front 42

What cell does PTH act on? What happens from there?

Back 42

1) Parathyroid hormone activates osteoblasts to secrete osteoclast-stimulating factor
2) this activates osteoclasts to resorb bone, thus elevating blood calcium levels

Front 43

where is calcitonin produced and what is its function?

Back 43

1) produced by parafollicular cells of the thyroid gland
2) It eliminates the ruffled border of osteoclasts and inhibits bone-matrix resorption, thus preventing the release of calcium.

Front 44

What are synarthroses? Where are they found?

Back 44

1) immovable joints composed of connective tissue, cartilage,
or bone
2) These joints unite the first rib to the sternum and connect
the skull bones to each other

Front 45

What are diarthroses also called? What is function?

Back 45

1) synovial joints
2) permit maximum movement and generally
unite long bones

Front 46

What is synovial fluid rich in?

Back 46

viscous fluid that is rich in hyaluronic acid and proteins

Front 47

What is the external capsule of a synovial joint composed of?

Back 47

The external (fibrous) capsular layer is a tough, fibrous layer of
dense connective tissue.

Front 48

What is the internal capsule of a synovial joint composed of?

Back 48

1) internal (synovial) capsular layer is also called the synovial
membrane
2) It is lined by a layer of squamous to cuboidal epithelial cells on its internal surface.
3) Two cell types are displayed in electron micrographs
of this epithelium.
a. Type A cells are intensely phagocytic and have a well-developed
Golgi complex, many lysosomes, and sparse RER.
b. Type B cells resemble fibroblasts and have a well-developed RER;
these cells probably secrete synovial fluid.