Bone histology

Question 1

bone is a connective tissue characterised by minneralized extracellular matrix.

The mineral is ______ ________ in the form of hydroxyapatite crytals

Bone matrix mainly contains type ____ collagen along with other non-collagenous proteins such as:
*
*
*
*

Answer 1

bone is a connective tissue characterised by minneralized extracellular matrix.

The mineral is CALCIUM PHOSPHATE in the form of hydroxyapatite crytals

Bone matrix mainly contains type 1 collagen along with other non-collagenous proteins such as:
*proteoglycans
*glycoproteins
* bone specific vitamin K-dependent proteins
* growth factors + cytokines

Question 2

lacunae are connected through small tunnels called _____

Answer 2

lacunae are connected through small tunnels called canaliculi

Question 3

what is Hyaline cartilage

Answer 3

Hyaline cartilage is the glass-like (hyaline) and translucent cartilage found on many joint surfaces. It is also most commonly found in the ribs, nose, larynx, and trachea. Hyaline cartilage is pearl-gray in color, with a firm consistency and has a considerable amount of collagen.

It looks slightly basophilic overall in H&E sections. Hyaline cartilage has widely dispersed fine collagen fibres (type II), which strengthen it. The collagen fibres are hard to see in sections. It has a perichondrium, and it is the weakest of the three types of cartilage.

Hyaline cartilage at the ends of your bones is sometimes referred to as articular cartilage. Hyaline cartilage is slippery and smooth which helps your bones move smoothly past each other in your joints. It’s flexible but strong enough to help your joints hold their shape

Question 4

what is perichondrium

Answer 4

The perichondrium is a dense layer of fibrous connective tissue that covers many types of cartilage in the body, whereas the periosteum is a thin layer of membranous connective tissue that covers all bones in the body.

Question 5

outersurface of bones are covered by periosteum except _____

Answer 5

outersurface of bones are covered by periosteum except where they articulate with other bones

Question 6

the lining of the cavity of both compact + spongy bone is called _____ ; it consists of

Answer 6

the lining of the cavity of both compact + spongy bone is called ENDOSTEUM; consists of a layer of osteoprogenitor cells (which differentiate to osteoblasts): endosteal cells

Question 7

difference between periosteum + endosteum

Answer 7

The periosteum is the sheath outside your bones that supplies them with blood, nerves and the cells that help them grow and heal. The endosteum is a membrane that lines the center of your bones that contain bone marrow

Question 8

Mature spongy bone has no _____ whereas mature cortical bone does

Answer 8

Mature spongy bone has no osteons whereas mature cortical bone does

Compact bone, microscopically, is made of numerous osteons, whereas spongy bone is composed of sheets of lamellar bone and does not contain osteons

Question 9

Lamellar bone has alignment of the collagen fibers and mineral phase. Mature lamellar bone exists as ______ (also called compact) or _____ (cancellous, spongy) bone.

Answer 9

Lamellar bone has alignment of the collagen fibers and mineral phase. Mature lamellar bone exists as cortical (also called compact) or trabecular (cancellous, spongy) bone.

Question 10

describe the histological features of the following:
1) woven bone {newly calcified/immature/primary bone}
2) lamellar bone {mature bone/secondary bone remodelled from woven bone}
3) compact bone {aka cortical bone; 80% of all lamellar bone}
4) cancellous bone (aka spongy/medullary bone; 20% of all lamellar bone)

Answer 10

1) woven bone {newly calcified/immature}= irregular + random arrangement of cells + collagen; lightly calcified

2) lamellar bone {mature bone remodelled from woven bone}= parallel bundles of collage in thin layers (lamellae) with regularly spaced cells between; heavily calcified

3) compact bone {aka cortical 80% of all lamellar bone}= parallel lamellae or densely packed osteons; with interstitial lamellae

4) cancellous bone (aka spongy; 20% of all lamellar bone)= interconnected thin spicules or trabeculae covered by endosteum

Question 11

where are osteoprogenitor cells derived from

Answer 11

osteoprogenitor cells are derived from mesenchymal cells

Question 12

bone lining cells derive from ______ and cover the bone, when it’s not remodelling

these bone lining cells are called ______ cells when they cover the external surface

and _______ cells when they cover the internal surface

Answer 12

bone lining cells derive from OSTEOBLASTS and cover the bone, when it’s not remodelling

these bone lining cells are called PERIOSTEAL cells when they cover the external surface

and ENDOSTEAL cells when they cover the internal surface

Question 13

During inflammation T lymphocytes produce RANKL molecules; inflammation can stimulate ______ activity

Answer 13

During inflammation T lymphocytes produce RANKL molecules; inflammation can stimulate OSTEOCLAST activity

n.b. when resorption is completed osteoclasts undergo apoptosis

Question 14

The _________ in the periosteum are responsible for appositonal growth (growth in width)

Answer 14

The OSTEOBLASTS in the periosteum are responsible for appositonal growth (growth in width)