Lecture 7: Histology I: Cartilage Flashcards

1
Q

bone and cartilage are specialized CT formed from ?

A

mesecnchyme derived from mesoderm

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2
Q

what does the lateral plate mesoderm form

green arrow

A

limb skeleton and sternum

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3
Q

what does the paraxial mesoderm form

light blue arrow

A

vertebrae, ribs and some of the skull

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4
Q

what does the neural crest form

A

parts of the skull

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5
Q

perichondrium cartilage is composed of how many layers and what are they

A

2 (outer fibrous and inner cellular)

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6
Q

what is the outer fibrous layer of cartilage composed of ?

A
  • dense CT
  • type I collagen
  • fibroblasts
  • vasculature
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7
Q

what it the inner cellular layer of cartilage composed of ?

A

chondrogenic cells = cartilage stem cells
- impt for appositional growth, maintenance and some repair

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8
Q

what cell type is arrow pointing to

A

chondrogenic cell = cartilage stem cell, a specialized fibrocyte producing cartilage ECM

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9
Q

characteristics of the chondrogenic cells

A
  • narrow and spindle shaped
  • ovoid nucleus w/ one or two nuclei
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10
Q

function of chondrocytes

A

secrete ECM

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11
Q

characteristics of Chondrocytes?

A
  • ovoid to rounded shape
  • large nucleus with prominent nucelolus
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12
Q

what cells are the blue arrows pointing to

A

chondrocytes

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13
Q

what type of cell is this?
what do the colored arrows each refer to

A

Chondrocyte

  • blue = euchromatin
  • pink = golgi
  • yellow = rER
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14
Q

term for chondrocytes that are actively secreting ECM

A

chondroblasts

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15
Q

As ECM forms around a chondroblast, it forms a ______, a fluid filled space where the inactive chondrocyte resides

A

lacuna

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16
Q

what is the blue arrow pointing to ? yellow arrow? green arrow?

A

Blue = chondrocyte in lacuna
Yellow = empty lacuna
green = ECM

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17
Q

what is the composition of the extracellular matrix (ECM) of cartilage?

A

mostly water, supported by collagen fibers

18
Q

Why is all cartilage avascular

A
  • helps cartilage regulate fluid content to resist compression
19
Q

where does cartilage receive its blood supply since it is avascular itself?

A

from nearby CT, diffusion from periphery

20
Q

what are proteoglycan aggregates (PGAs)

A

very large aggregates of proteoglycans non-covalently bound to hylauronic acid

  • they create internal pressure (turgor) that allows cartilage to resist compression without inhibiting its flexibility
21
Q

what regions of matrix does each arrow point to

A

red = capsular matrix
- around chondrocytes
- many PGs
- very dark staining
blue = terrirorial matrix
- near chondrocytes
- type II fibrils, PGs
- dark staining
green = inter-territorial matrix
- away from chondrocytes
- few PGs
- pale staining

22
Q

ECM components exist to help regulate water content in order to resist ______

A

compression

23
Q

what cartilage type do these images depict

A

hyaline cartilage

  • no visible fibers
  • ECM stains pink or purple depending on the abundance of collagen
  • NEVER has elastic or type I collagen fibers in its ECM
24
Q

what cartilage type is this

A

elastic cartilage
- has elastic fibers in its ECM

25
Q

What do these images depict

A

fibrocartilage

  • type I collagen fibers
  • no perichondrium
  • chondrocytes of fibrocartilage are much larger and rounder than those in dense CT
26
Q

physical difference b/w chondrocytes found in fibrocartilage vs in dense CT

A
  • fibrocartilage chondrocytes are larger and rounder
  • dense CT chondrocytes are flatter and elongated
27
Q

what type of cartilage is this?

A

articular cartilage

28
Q

what is cartilage comprised of

A
  • large amount of functional ECM
  • small amount of chondrocytes
29
Q

what is articular cartilage and where is it found

A

a type of hyaline cartilage found on the surface of synovial joints

30
Q

what type of cartilage is this

A

hyaline
- has isogenous group
- no fibers

31
Q

what is this ?

A

subchondral bone
- bone supporting articular cartilage
- entirely covered by cartilage
- lacks chondrocytes

32
Q

explain the steady state of cartilage

A
  • maintained by chondrocytes
  • steady state allows for normal anabolic processes
    - synthesis of ECM components
    - equilibrium w/ normal catabolic processes
    - normal turnover of matrix molecules
33
Q

how does injury to the cartilage matrix affect the steady state balance

A

injury causes chondrocytes to release cytokines that inhibit ECM secretion and enzymes that digest the ECM instead of factors to produce more matrix

this results in cartilage degeneration

34
Q

fibrocartilage has no?

A

perichondrium

35
Q

p

A
36
Q

proteogylcans contain _________, which are molecules that attract water

A

Glycosaminoglycans (GAGs)

37
Q

what binds proteogylcans to eachother, forming proteoglycan aggregates

A

hylauronic acid

38
Q

ECM components of hyaline cartilage

A
  • PGAs, MGPs, type II collagen
39
Q

ECM components of elastic cartilage

A
  • PGAs, MGPs, type II collagen AND elastic fibers
40
Q

ECM components of fibrocartilage

A
  • PGAs, MGPs, type II collagen AND type I collagen for resistance to tension
41
Q

what is missing from articular cartilages that inhibits its ability to repair or scar

A

no perichondrium