Histology- connective tissues

Question 1

what cells do mesecchymal stem cells produce

Answer 1

mast cells, fibroblasts (mature to fibrocytes), chondroblasts (mature into chondrocytes), osteoblast (mature to osteocytes), white adipose tissue and brown adipose

Question 2

what cells do haemopatopoietic cells gove rise to

Answer 2

monocytes, macrophages, lymphocytes, possible mast cells

Question 3

Name 3 main constituients in connective tissue

Answer 3

cells (fibroblasts, adipose etc.) visible fibres (lay outside), and ground sunstance

Question 4

How would you tell the difference between adipose cells (present in fatty connective tissue) and fibroblasts (present in fibrous connective tissue)?

Answer 4

adipose cells stain lighter whereas fibroblasts stain darker.

Question 5

Give examples of 3 extracellular fibres

Answer 5

collagen, elastin and reticulin

Question 6

what is gound substance containing and can it be stained?

Answer 6

Ground substance cannot be stained with H+E, made of proteoglycans, glycosaminoglycans (GAG) and a number of invisible fibres e.g. laminin and fibronectin

Question 7

ways to describe connective tissue and example of each e.g. hard and soft, then loose and dense, irregular and regular example of each

Answer 7

hard- bone
soft- fibrous or fatty

Fibrous tissue can then be described as either loose or dense. Described as loose irregular if it contains few visible fibres that are randomly orientated or dense irregular if it contains large numbers of fibres with relatively little intervening amorphous matrix. Dense regular connective tissue contains large numbers of fibres that are all arranged in long parallel bundles. E.g. penis contains loose and dense irregular
- dense connective tissue can then be irregular (like in penile fascia) or regular (like in tendons)

Question 8

collagen- staining? what is it? how’s it made?

Answer 8

collagen is an extracellular fibre which is presnt within connective tissues, fibroblasts secrete tropocollagen subunits (triple helix of peptides), which then assembled extracellualry and run in non-unifrom bundles. Collagen stain pink with H+E.

Question 9

Name examples of where each tupe of collagen is found

Answer 9

Type 1 - bone, tendon, ligamnets and skin

Type 2 - articular cartilage, vitreous (jelly like substance at back of eye)

Type 3- forms scaffold in many solid organs- liver, bone marrow, spleen, shown below with silver stain (reticulin)

Type 4- basement membrane

Type 5 - placenta

Question 10

Elastin- what is it? Where produced? Staining?

Answer 10

Elastin is an extracellular fibre found in connective tissues, contain fine fibres and sheets of elastin, can be branched, similarly to collagen it is produced by fibroblasts, and stain pink with H+E, do elastin stain to distinguish between

Question 11

White adipose cells- what are they? How identify them?

Answer 11

found in fatty connective tissue, have large fat globule present which during processing is washed away so appear as large empty spaces (don’t confuse with image of lung), can also secrete hormones

Question 12

Brown adipose cells

Answer 12

Not particularly present in adults but very important in neonatl thermoregulation (genereate heat on breakdown), cells have many globules giving them there characteristic ‘foamy’ look

Question 13

Talk about hylaine cartilage- appearance?, fibres present? is a perichondrium presnt?

Answer 13

• Hyaline cartilage: Present in supporting ‘rings’ of the trachea and the cartilages of the larynx, present in synovial joints (no perichondrium here), chondrcytes sit in lacunae surrounded by a glassy amorphous matrix, no visible fibres (has small invicible elastic and collagen II fibres), have perichondrium (layer of fibrous connectibe tissue at edge made of fibroblasts and collagen, undifferentiated progenitor cells capable of differentiating into chondroblasts should the need arise.). AVASCULAR

Question 14

Elastic cartilage- appearance? fibres present? is a perichondrium presnt? where may find this?

Answer 14

Chondrocytes in lacunae surrounded by amophous matrix, elastin fibres presnt as well as (type II collagen), perichondrium (layer of fibrous connectibe tissue at edge made of fibroblasts and collagen). Can do stain to look for elastic present. found in epiglotts (a flap of tissue that sits beneath the tongue at the back of the throat) and pinna (external part of ear). AVASCULAR

Question 15

Fibrocartilage- give examples of where found?

Answer 15

chondrocytes sit in extracelular matrix with thick collagen (type I and II) fibres, perichondrium (layer of fibrous connectibe tissue at edge made of fibroblasts and collagen ). Found in annulus fibrous, pubic symphysis (found on the anterior side of the pelvis and is the anterior boundary of the perineum) and certebral discs. AVASCULAR

Question 16

smooth muscle

Answer 16

Smooth muscle:

• involuntary controll, fusiform cells, central nuclus, not striated nucleus and non-branching

Question 17

fibroblasts

Answer 17

appear as very small cells- little to no cytoplasm and a spindle nucleus

Question 18

name 3 other cells with contractile properties

Answer 18

pericytes- found around outside of some blood vessels, Myofibroblasts, myoepithelial cells.

Question 19

discuss features of smooth muscle

Answer 19

cells are connected by gap junctions (so can all contract at same time), When cut longitudinally the cells appear elongated with tapered ends (fusiform) and their nuclei appear cylindrical. When sectioned transversely both the cells and their nuclei appear round. Smooth muscle cells are anchored focally (in clumps) to the inside of the cell membrane, secrete a reticulin-rich external lamina (basement membrane) that joins the cells together.

Question 20

what do fibroblasts do

Answer 20

secrete extracellular matrix components e.g. collagen and elastin

Question 21

what do chondrocytes do

Answer 21

secrete extracellular matrix component of cartilage

Question 22

what do osteoblacts do

Answer 22

secrete the extracellular matrix components of bone

Question 23

what do adipocytes do

Answer 23

lipid storage which act as energy store

Question 24

what is the extracellular matrix within cartilage

Answer 24

The extracellular matrix is the bioscaffold of tissues and is composed mainly of fibrillar proteins (such as collagen, elastin) surrounded by glycosaminoglycans (e.g. hyalaronic acid) and proteoglycans (e.g. chondroitin sulphate, keratan glycan).

Question 25

synovium

Answer 25

lines joint capsule, 1-4 layers of synovial cells, Tyoe A- phagocytes, Type B-rich in rER, vary in shapes and are richlu vascular and highly innervated