Histology

1. HISTOLOGY OF CARTILAGE
Dr. Rabia Inam Gandapore
Assistant Professor
Head of Department Anatomy
(Dentistry-BKCD)
B.D.S (SBDC), M.Phil. Anatomy (KMU),
Dip. Implant (Sharjah, Bangkok, ACHERS) , CHPE
(KMU),CHR (KMU), Dip. Arts (Florence, Italy)

2. Teaching Methodology
 LGF (Long Group Format)
 SGF (Short Group Format)
 LGD (Long Group Discussion, Interactive discussion with the use of models or diagrams)
 SGD (Short Group)
 SDL (Self-Directed Learning)
 DSL (Directed-Self Learning)
 PBL (Problem- Based Learning)
 Online Teaching Method
 Role Play
 Demonstrations
 Laboratory
 Museum
 Library (Computed Assisted Learning or E-Learning)
 Assignments
 Video tutorial method

3. Goal/Aim (main objective)
 To help/facilitate/augment the students about the:
1. Define cartilage.
2. Describe components of cartilage.
3. Describe histological characteristics of cartilage.
4. Classify cartilage on basis of histological features.

4. Specific Learning Objectives (cognitive)
At the end of the lecture the student will able to:
1. Recognize components & histological characteristics of cartilage.
2. Classify cartilage on basis of histological features
 Sketch labeled diagram of the Hyaline , Fibrocartilage and Elastic Cartilage

5. Psychomotor Objective: (Guided response)
 A student to draw labelled diagram of Hyaline , Fibrocartilage and Elastic
Cartilage

6. Affective domain
 To be able to display a good code of conduct and moral values in the class.
 To cooperate with the teacher and in groups with the colleagues.
 To demonstrate a responsible behavior in the class and be punctual, regular, attentive and
on time in the class.
 To be able to perform well in the class under the guidance and supervision of the teacher.
 Study the topic before entering the class.
 Discuss among colleagues the topic under discussion in SGDs.
 Participate in group activities and museum classes and follow the rules.
 Volunteer to participate in psychomotor activities.
 Listen to the teacher's instructions carefully and follow the guidelines.
 Ask questions in the class by raising hand and avoid creating a disturbance.
 To be able to submit all assignments on time and get your sketch logbooks checked.

7. Lesson contents
Clinical chair side question: Students will be asked if they know what is the function of cartilage
Outline:
 Activity 1 The facilitator will explain the student's about:
1. Components & histological characteristics of cartilage.
2. Classify cartilage on basis of histological features.
 Activity 2 The facilitator will ask the students to make a labeled diagram of the Hyaline ,
Fibrocartilage and Elastic Cartilage
 Activity 3 The facilitator will ask the students a few Multiple Choice Questions related to it with
flashcards.

8. Recommendations
 Students assessment: MCQs, Flashcards, Diagrams labeling.
 Learning resources: Langman’s T.W. Sadler, Laiq Hussain Siddiqui, Snell Clinical Anatomy, Netter’s
Atlas, BD Chaurasia’s Human anatomy, Internet sources links.

9. Cartilage
 DEFINE CARTILAGE.
 DESCRIBE COMPONENTS OF CARTILAGE.
 DESCRIBE HISTOLOGICAL CHARACTERISTICS OF CARTILAGE.
 CLASSIFY CARTILAGE ON BASIS OF HISTOLOGICAL FEATURES.

10. Cartilage
 Cartilage is a specialized form of firm, flexible, semi-rigid & resilient
connective tissue that can bear mechnical stresses without permanent
distortion.
 It consists of:
1. Cells
a. Chondroblasts forms Chondrocytes inside lacunae (inside ECM)
2. Extracelluar matrix (consisting of Connective Tissue fibers & ground
substance)
a. Hyaluranan
b. Proteoglycans
c. Glycoproteins. Glycosaminoglycans
d. Collagen fibers
e. Elastic Fibers
 Avascular tissue, Diffusion (Nutrients & waste, Co2).
 Incase of Synovial joints nutrition received via synovial fluid
 Serves as a precursor or model for embryonic development & subsequent
growth of many long bones.Its replaced by bone tissue in adult life, except
for surfaces that articulate with other bones

13. Components of Cartilage
 Cartilage has
1. Cells: Chondrocytes inside lacunae in the
extracellular matrix. Extracellular matrix secreted by
chondrocytes
2. Extracellular Matrix: Makes cartilage resilient in
nature
a. Ground substance
1. Glycos-amino-glycans
2. Proteo-glycans
b. Connective tissue fibers
1. Collagen fibers
2. Elastic fibers
3. Perichondrium: Dense irregular Connective tissue,
Covers cartilage
a. Outer: Fibrous Layer
1. Collagen
2. Fibroblast
3. Blood vessels
4. Lymphatic's
5. Nerves
a. Inner: Cellular Layer
1. Chondrogenic cells= transforms into chondroblast
(Cartilage forming cells)

14. Function
 Shock absorber
 Gliding surface, permits friction
free movement of joints
(Synovial joint)

15. Classification
 Based on type of Fibers , Fibrils in Extracellular matrix
1. Hyaline Cartilage: Collagen Type-II only
2. Fibrocartilage: Collagen Type-I and Collagen Type-II matrix
3. Elastic Cartilage: Collagen Type-II & Elastic

16. Types
 3 types of cartilage:
1. Hyaline cartilage (Type II collagen)
 Articular surfaces
 Ephiphyseal plate
 Tracheal wall, etc.
2. Elastic cartilage (Type II collagen, elastic fibers)
 Pinna of the ear
 Epiglottis
 Eustachian tube, etc.
3. Fibrocartilage (Type II and Type I collagen)
 Intervertebral disks
 Pubic symphysis
 insertion sites of tendons and ligaments

17. 1. Hyaline Cartilage
Morphology:
 Glass like appearance (lacks periodicity)
 No nerves & blood vessels
 Bluish white translucent appearance
 Covered by perichondrium (Except synovial joint)
 Abundant extra-cellular matrix, cells & Perichondrium
Location:
 Fetus (Cartilage converts to bone)
 Adult-Epiphyseal cartilage of growing bones (Long bones)
 Costal cartilage (Ribs & Sternum)
 Nasal Cartilage/ septum
 Arytenoid cartilage/ Larynx
 Cartilage of tracheal rings and bronchi
 Esophagus

19. Hyaline Cartilage
Function
 Support
 Resist compressive stress
 Flexibility
 Shock absorber (Due to presence of GAG’s Proteoglycans)
Contents
1. Extracellular matrix (Abundant & basophilic): Secreted by chondrocytes, Cannot be seem under light microscope
a. Collagen Type II (Traces of Collagen Type 9,10 & 11)
b. Proteoglycans: Abundant
1. Glyco-amonoglycans (Shock absorber property)
2. Keratin sulfate
c. Glycoproteins
1. Chondro-nectin (Binds chondrocytes to ECM)
2. Chondro-calcin
d. Water

20. Hyaline Cartilage
2. Cells: Protein secreting cells, aligns along perichondrium
a. Chondrocytes
 Large & Spherical
 Central Nucleus (2 nuclei)
 Granular cytoplasm
 Basophilic
 Fat Droplets
 Glycogen granules
 Large amount of RER
 Golgi apparatus
 Lies within lacunae surrounded by ECM
 Protoplasmic processes (False star shaped appearance)
b. Isogenous group
 Spherical/ Ovid/ flattened
 Present in center of hyaline
cartilage
 2-4 cells group
 Single chondrocyte progeny (By
mitotic division of original
chondrocytes
 All member occupy single
lacunae

21. Hyaline Cartilage
3. Perichondrium
a. Fibrous layer (Outer): Collagen fibers,
fibroblast, blood vessels, Lymphatic's,
Nerves
b. Cellular layer (Inner): Chondrogenic cells
transform to chondroblast, cartilage forming
cells)

22. 1. Free mesenchymal cells (Hemo-cytoblast)
 Mega-karyoblast= Mega-karyocyte= Thrombocytes (Platelets)
 Monoblast= Monocytes
 Lymphoblast= Lymphocytes
 Myeloblast= myelocyte (Progranulocytes)=
a. Basophil
b. Eosinophil
c. Neutrophil
 Basophillic erythroblast (Proerythroblast)= Polychromatic
erythroblast= Normablast= Erythrocyte
2. Fixed undifferentiated mesenchymal cells
Agranulocytes
Granulocytes

23. 2. Fixed undifferentiated mesenchymal cells
(Bone marrow, Muscles, Adipose, Umblical cord)
 Fixed Macrophages= Free macrophages
 Fibroblast= Tendon & Ligament
 Osteoblast= Osteocytes= Bone
 Chondroblast= Chondrocyte= Cartilage
 Adipocyte= Adipose (Fat cells)
 Mast Cells
 Granulocytes
 Endothelial cells line the embryo

24.  Cartilage is formed from
mesoderm germ layer by
the process known as
chondrogenesis.
 Mesenchyme
differentiates into
chondroblasts, which are
the cells that secrete the
major components of the
extracellular matrix—the
most important of these
components for cartilage
formation being aggrecan
and type II collagen

28. Cartilage growth
 Appositional Growth: Deposition of
new cartilage on surface of existing
cartilage.
 Interstitial Growth: Formation of new
cartilage within an existing cartilage.

30. Repair of Hyaline Cartilage
 Small Injury: Repaired by chondrogenic cells of
perichondrium- Chondroblast= Repair site and
new cartilage matrix
 Large Injury: Peri-chondrial fibroblast produce
scar of dense connective tissue to fill the defects.

34. Cartilage Matrix
 Type II collagen
 Hyaluranan (hyaluronic acid) up to 8X106 d
 Proteoglycans (3.5X106 daltons)
1. Aggrecan
2. Protein Core
3. Glycosaminoglycans (GAGs)
4. Chondroitin sulphate
5. Keratin sulfate

36. Cartilage Matrix & Its function
 Glycosaminoglycans (GAGs) tend to adopt highly
extended, so called random coil conformations, which
occupy a huge volume relative to their mass and they
form gel.
 Their high density of negative charges attract cations,
such as Na++ that are osmotically active causing large
amounts of water to be sucked into the matrix.
 This creates a swelling pressure or turgor, that enables
the matrix to withstand compressive forces (in contrast
to collagen fibers which resist stretching forces).
 Cartilage matrix resist compression by this mechanism.

40. Cartilage Changes with Aging
 Not much changes with collagen.
 Proteoglycans produced in older individuals are smaller with shorter chondroitin sulfate chains
than in younger individuals.
 Chondrocytes seem less efficient in renewing the matrix thus reducing proteoglycan contents.
 These changes might reduce water contents in the matrix and make the cartilage less able to
resist compressive forces.
 These changes, in turn, would make matrix more vulnerable to injuries in weight-bearing, and the
inflammatory response to injury would cause painful symptoms of arthritis.

41. 2. Fibrocartilage
Morphology:
 Dense irregular C.T with hyaline cartilage (alternating bands of both)
 No Perichondrium
 Show periodicity
 Chondrocytes= Parallel row 2, 4, 6 cells (Isogenous group cells)
 Collagen type I and Collagen type II matrix
 Fibroblast
 Isogenous group cells surrounded by increased territorial matrix ( Increase proteoglycans,
sulphate GAGS, chondroitin sulphate , basophilic)
 Inter-territorial matrix replaced by collagen Type-I
 Increase collagen Type-I (Acidophillic)
 Fibrocartilage develops from fibroblast= Chondrocytes (increased collagen type-I) secrete
proteoglycans matrix

43. Function:
 Increased strength= Rigidity
 Flexibility
 Movement ball & socket Joints
Location:intermediate between cartilage and dense regular connective tissue.
 Intervertebral discs (Nucleus pulposus)
 Disc of pubic symphysis
 Intra-articular discs of the sterno-clavicular & TMJ
 Menisci of knee joint
 Labrum glenoidale of shoulder joint
 Labrum acetabulum of hip joint
 Ligamentum teres of hip joint
 Found where tendon & ligaments attach to bone

44. 3. Elastic Cartilage
Morphology:
 Flexible (returns to original shape)
 Yellowish, opaque matrix eosinophillic
 Condrocyte= Lacunae, more cellular
a. Single
b. Isogenous group
 Elastic fibers (esp around chondrocytes)
 Stains : Von Greson’s stain specific for elastin)
 Collagen Type-II
 Perichondrium (Fibrous & Cellular)
 Develops by
a. Interstitial growth
b. Appositional growth
 Doesnot go calcified
 Cannot be seen on H& E stain ( Van Greson’s, aldehyde fuchsin, masson’s trichrome)

46. Function:
 Flexibility
 Stretch
 Withstand repeated bending, reduce friction between the bone
 Contracts
 Location:contains elastic fibers.
 Auricle (Pinna) External Ear
 Epiglottis of larynx
 External auditory meatus.
 Auditory tube (auditory canal, Eustachian tube)
 Skin

49. Thank You
 ANY QUESTIONS?