Practical 3 - Connective Tissues

Question 1

What cell do most connective tissue cells arise from?

Answer 1

Undifferentiated mesenchymal cell

Question 2

What cells arise from undifferentiated mesenchymal cells?

Answer 2

• mast cells
• white & brown adipocytes
• fibroblasts, differentiate into fibrocytes
• chondroblasts, differentiate into chondrocytes
• osteoblasts, differentiate into osteocytes

Question 3

Where else are connective tissue cells derived from?

Answer 3

Haematopoetic stem cell line

Question 4

Which cells are derived from the haematopoetic stem cell line?

Answer 4

• monocytes
• macrophages
• lymphocytes
• mast cells

Question 5

Constituents of connective tissue?

Answer 5

• cells
• visible fibres (collagen, elastin, reticulin)
• ground substance (hydrophilic jelly which appears as white space on H&E stained specimen) contains proteoglycans, glycosaminoglycans and invisible fibres (laminin, fibronectin)

Question 6

Three types of connective tissues?

Answer 6

• fibrous
• hard
• fatty

Question 7

2 types of fibrous connective tissue?

Answer 7

• loose

- dense

Question 8

2 types of hard connective tissue?

Answer 8

• cartilage

- bone

Question 9

How is collagen formed?

Answer 9

• fibroblasts secrete tropocollagen subunits

- tropocollagen subunits are assembled into collagen fibres extra-cellularly

Question 10

How many types of collagen are there?

Answer 10

> 20 types

Question 11

Where is type 1 collagen found?

Answer 11

Skin & bone

Question 12

Where is type 2 collagen found?

Answer 12

Cartilage

Question 13

Where is type 3 collagen found?

Answer 13

Liver, bone marrow, spleen.

Reticulin is type 3 collagen.

Question 14

Where is type 4 collagen found?

Answer 14

Basement membranes

Question 15

Where is type 5 collagen found?

Answer 15

Placenta

Question 16

How do collagen fibres appear on H&E stains?

Answer 16

Extracellular fibres stained pink, often run in bundles.

Question 17

What does loose connective tissue comprise?

Answer 17

• widely spaced thin collagen fibres
• fibroblasts/ fibrocytes
• ground substance

Question 18

What does dense connective tissue comprise?

Answer 18

• closely spaced thick collagen fibres
• fibroblasts/fibrocytes
• ground substance

Question 19

Example of irregular dense connective tissue?

Answer 19

Penile fascia

Question 20

Example of regular dense connective tissue?

Answer 20

Tendon

Question 21

Function of reticulin?
Where is reticulin found?
Can it be seen on H&E stain?

Answer 21

• forms a supporting scaffold in many organs
• bone marrow, liver, kidney, lymph node, spleen
• not visible on H&E stain, need silver stain

Question 22

What does elastin comprise?

Answer 22

Fine fibres and sheets of elastin.

Fibres may be branched.

Question 23

What produces elastin?

Answer 23

Fibroblasts

Question 24

Histological appearance of elastin?

Answer 24

Stained pink by H&E, easily confused with smooth muscle.

Question 25

Characteristics of white adipose tissue?

Answer 25

Large cells, single fat globule in each. Nucleus pushed to one side by fat globule.

Question 26

Histological appearance of white adipose tissue?

Answer 26

Appear white and empty as fat is extracted during processing. Nucleus pushed to one side.

Question 27

Features of brown adipose tissue?

Answer 27

- each cell contains many fat globules - found across shoulders in adults, down the back in newborns - important in neonatal thermoregulation as breakdown of tissue generates heat

Question 28

Constituents of cartilage?

Answer 28

- chondroblasts and chondrocytes - extracellular matrix comprises glycosaminoglycans (e.g. hyaluronic acid) and proteoglycans (condroitin sulfate and keratan glycan) - extracellular fibres (collagen and elastin)

Question 29

Does cartilage contain blood vessels?

Answer 29

No, it is avascular.

Question 30

What does hyaline cartilage comprise? | Where is it found?

Answer 30

Chondrocytes in lacunae (cavities) surrounded by a glassy matrix. No visible fibres. Perichondrium consists of fibroblasts and collagen. Found in synovial joints.

Question 31

What does elastic cartilage comprise? | Where is it found?

Answer 31

Chondrocytes in matrix which contains visible elastic fibres. Perichondrium consists of fibroblasts and collagen. Found in the pinna (outer ear) and epiglottis.

Question 32

What does fibrocartilage comprise? | Where is it found?

Answer 32

Chondrocytes in a matrix containing visible collagen fibres. Perichondrium consists of fibroblasts and collagen. Found in the annulus fibrosus (circular exterior of intervertebral discs, surrounding the nucleus pulposus). Also found in the pubic symphysis.

Question 33

What is synovium, and what does it comprise? | What are the 2 types of synovial cells?

Answer 33

Lining of inside of joint capsule. Consists of 1-4 layers of synovial cells of variable shapes (squamous to cuboidal). Richly vascular and highly innervated. Type A cells - phagocytes Type B cells - rich in rough ER

Question 34

Where is visceral (smooth) muscle found?

Answer 34

- arterial wall - intestinal wall - airways of lungs - reproductive and urinary tracts

Question 35

Where is voluntary (skeletal) muscle found)?

Answer 35

- skeletal muscles - larynx - diaphragm

Question 36

Where is cardiac muscle found?

Answer 36

- heart | - base of great vessels

Question 37

3 examples of contractile cells (other than muscle)? | Where are they found?

Answer 37

Pericytes - around the outside of capillaries. | Myo-fibroblasts and myo-epithelial cells - found in and around ducts.

Question 38

Features of smooth muscle?

Answer 38

- involuntary - fusiform cells - central nucleus - no striations or branching - cytoplasm stained pink by eosin