Connective tissue histology

Question 1

Composition of basal lamina/basement membrane

Answer 1

a specialized ECM made of collagen, laminin, other glycoproteins

Question 2

Answer 2

macrophages

Question 3

Answer 3

fibroblasts

Question 4

Elastic fibers structure and function

Answer 4

• made of elastin and microfibrils (made of fibrillin)
• random coiling of elastin molecules gives elasticity
• elastin is secreted from fibroblasts as an amorphous monomer tropoelastin which is then crosslinked extracellularly into fibers
• in the absence of fibrillin, elastin would assemble into sheets not fibers

Question 5

Answer 5

adipocyte

Question 6

Adipose tissue function

Answer 6

energy storage, insulation, protection

Question 7

General purpose of connective tissue

Answer 7

Support for other types of tissues

Question 8

Oil red O stain

Answer 8

For fat/lipid (H&E doesn’t stain)

Question 9

Collagen structure and function

Answer 9

• most common ECM fibrous protein
• resists forces
• 3 chains wrapped in a helix (requires vitamin C) and crosslinked for extra tensile strength
• released from cells as procollagen and processed extracellularly

Question 10

adipocytes

Answer 10

fat storage

Question 11

Composition of reticular connective tissue

Answer 11

• branched, interconnecting network of very fine collagen (III) fibers

Question 12

Answer 12

Loose connective tissue

Question 13

Adipose tissue composition

Answer 13

adipocytes

Question 14

Where is connective tissue derived from embryologically?

Answer 14

Mesoderm

Question 15

What is the function of loose connective tissue

Answer 15

• “packing material”
• nutrient source for epithelium

Question 16

Dense irregular connective tissue

Answer 16

• impact resistant against multidirectional forces
• found in joint capsules, under skin (dermis), and fascia

Question 17

Answer 17

Mast cells

Question 18

H&E stain

Answer 18

• eosin stains acidophiles (it is anionic/acidic)
• hemotoxylin stains basophiles (it is cationic/basic)
• stains nuclei darker and cytoplasm pink

Question 19

Answer 19

reticular fibers

Question 20

Answer 20

other WBCs: neutrophils, plasma cells, lymphocytes, eosinophils

Question 21

Answer 21

Dense regular connective tissue

Question 22

Ground substance

Answer 22

• Gel like susbstance rich in GAGs (negatively charged, repeating, unbranched disaccharides that bind water)
• mechanical support, hydrates tissue, regulates cell migration and reaction to environment
• also contains proteoglycans (GAGs attached to linear core protein) and multiadhesive glycoproteins that have binding sites for components of connective tissues and basal cell membranes of epithelia (leading to stabilization)

Question 23

Composition of dense connective tissue

Answer 23

woven collagen fibers in a matrix with elastin (irregular) or parallel collagen fibers (regular)

Question 24

Fibroblasts/myofibroblasts

Answer 24

• structural support (primary workhorses)
• wound healing

Question 25

Middle layer

Answer 25

Loose connective tissue

Question 26

Defining features of connective tissue

Answer 26

- cells separated by/surrounded by an ECM (type of ECM defines type of tissue) - serves functional role of support, nutrient/gas exchange, fat storage, defense/protection, and healing/remodeling

Question 27

Components of ECM

Answer 27

collagen fibers, elastin fibers, ground substance

Question 28

Functions of basal lamina/basement membrane

Answer 28

- separates epithelial cells from and anchors them to underlying connective tissue - can act as a filter - can play a role in cell-cell communication

Question 29

ECM function

Answer 29

structural and biochemical/nutritional support for other tissues

Question 30

Mast cells

Answer 30

- defense (recognize pathogens and release immune mediators) - healing and remodeling

Question 31

Answer 31

Dense irregular connective tissue

Question 32

Cells of connective tissue

Answer 32

- fibroblasts/myofibroblasts - macrophages - mast cells - plasma cells, lymphocytes, eosinophils - adipocytes

Question 33

Composition of loose connective tissue

Answer 33

- many cell types - few fibers (elastic/collagen) - high fat content - high amount of ground substance

Question 34

Dense regular connective tissue

Answer 34

- resistant to tension forces (lengthening) - found in tendons/ligaments

Question 35

Where is loose connective tissue found?

Answer 35

- Superficial fascia under the skin - colonic submucosa

Question 36

Macrophages

Answer 36

- structural support - healing and remodeling - phagocytic and involved in immune response

Question 37

Reticular connective tissue function and location

Answer 37

- supportive tissue - meshwork; allows cells to pass through - found in lymphatic tissues (except thymus) and hematopoietic tissues

Question 38

Collagen types

Answer 38

I = most common; bone, skin, tendons, ligaments, cornea I, II, III, V, and IX are fibrilar (form 10-300nm fibrils) V and VI in basal lamina