Charles University in Prague, First Faculty of Medicine
Tissues - classification, general structure and
function. Connective tissue - general
characterization. Extracellular matrix - its synthesis
and composition. Cartilage - structure and function.
Doc. MUDr. Marie Jirkovská,CSc
Institute of Histology and Embryology
Subject: GHGE
Code: B82241
Tissue – organized aggregation of cells that
function in a collective manner.
Cells in the tissue have common origin,
morphological characteristics and organization.
Tissues are responsible for maintaining body
functions.
All organs are made up from only four
basic tissue types:
•epithelial tissue (epithelium),
•connective tissue,
•muscle tissue,
•nerve tissue
Each type may be further subdivided.
Epithelium (epithelial tissue) – covers body surface, lines body
cavities and forms glands. Originates directly from germ layer.
Epithelium of the urinary bladder
Secretory epithelium of pancreas
Connective tissue – structurally and functionally underlies and
supports the orther three basic tissues. Originates from
mesenchyme. Cells are separated from one another by their
product extracellular matrix (ECM).
Dense connective tissue (tendon)
Hyalinne cartilage
Muscle tissue - responsible for movement. Originates from
mesoderm or mesenchyme.
Smooth muscle tissue
Skeletal muscle
Nervous tissue - receives, transmits and integrates information
from outside and inside the body to control the activities of the
body. It originates from neuroectoderm.
Spinal cord
Peripheral nerve
Connective tissue developed from mesenchyme, cells are separated from
one another by their product - extracellular matrix
(ECM).
Classification of connective tissue:
•Connective tissue proper
•Cartilage
•Bone
•Dentin
•Cementum
Connective tissue proper
Classification:
Dental pulp,
umbilical cord
Jelly-like
(mucous)
connective
tissue
Mesenchyme
Spleen,
lymph nodes,
bone marrow
Reticular
connective
tissue
Interstitial, e.g.
stroma of epithelial
organs
Adipose
tissue
Loose
connective
tissue
Dense
connective
tissue
Tendons,
ligaments,
aponeuroses
White
(unilocular
Storage of energy adipocytes)
Brown
(multilocular
adipocytes)
Newborns
Regular
(arrangement
of ECM
fibrillar
component)
Sclera, dermis
Irregular
(arrangement
of ECM
fibrillar
component)
Jelly-like c.t.
Dense regular c.t.
Loose c.t.
Reticular t.
Dense irregular c.t.
White adipose t.
Connective tissue cells:
resident:
• fibroblast
• fibrocyte
• myofibroblast
• adipocyte – unilocular
multilocular
• melanocyte (pigment
cell) (originating from
the neural crest)
• adult stem cells
free (wandering):
• histocyte – macrophage
• granulocyte – neutrophilic
eosinophilic
basophilic
• lymphocyte
• monocyte – precursor of
macrophage
• plasma cell – effector of immune
response
• mast cell – heparin and histamin –
Resident cells
adipocytes
fibroblasts in the lamina propria
mucosae of gallbladder
mikrograph: Wheater´s Funct. Histology, 2000
pigment cells
fibrocytes
(melanocytes)
in uvea
Wandering cells
eosinophils in lamina propria
of the intestinal villus
macrophages in a lymphnode
heparinocytes
(mast cells)
plasma cell
Extracellular matrix (EMC)
produced by cells
(fibroblasts, chondroblasts, osteoblasts,…)
consists of
fibrillar component
(collagen fibres - type I collagen, reticular fibres - type III
collagen, elastic fibers (elastin, fibrillin)
and
ground (amorphous) substance
(GAGs, proteoglycans, adhesive glycoproteins)
Connective tissue fibres
produced by fibroblasts, composed of proteins consisting of long peptide chains
Collagen fibres = bundles of collagen fibrils
(the fibril is 20-300 nm in diameter; 68 nm
banding pattern reflects the size, shape and
arrangement of collagen molecules)
micrograph by atomic force microscopy
Intracellular
events
Synthesis
of collagen
fibres
Extracellular
events
Kierszenbaum: Histology
and Cell Biology 2007
Structure and synthesis
of elastic fibres
Kierszenbaum: Histology and Cell Biology 2007
Ground (amorphous) substance
a viscous clear substance with high water
content composed of
• hyaluronan (a carbohydrate chain of thousands
of sugar molecules - glucuronic acid and N-acetylglucosamin, it forms dense hyaluronan network) abundant in ECM
• proteoglycans (= core proteins and GAGs
(glycosaminoglycans)
•glycosaminoglycans = long unbranched chains
composed of repeating disacharide units (e.g.
chondroitinsulfates, heparansulfate,…),
negatively charged (sulfate and carboxyl groups)
• multiadhesive glycoproteins - stabilizing the
EMC and linking it to cell surface (fibronectin,
laminin, tenascin, osteopontin)
GAGs
Proteoglycan aggregate
Proteoglycans
Ross, Pawlina: Histology, 2005
Interrelationship of cell and EMC
Co = collagen fibril, F = fibronectin, HA = hyaluronan,
MF = actin filament, PG = proteoglycan, R = integrine
Organization
of loose
connective
tissue
Ross, Pawlina: Histology, 2005
Interrelationship of epithelial cell and EMC
Ross, Pawlina: Histology, 2005
Cartilage
is an avascular tissue formed by
Cells:
chondroblasts, chondrocytes (product
and maintain ECM = carry out
matrix turnover)
chondroclasts (originate from fused
mononuclear macrophages precursors,
function: removal of cartilage during endochondral bone formation)
ECM: solid and firm, but pliable
fibrillar component - collagen fibrils (collagen type I and II) and elastic
fibrils (elastin & fibrillin)
amorphous component - hyaluronan, proteoglycans,
glycosaminoglycans (aggrecans), minor collagens (VI, IX, X, XI)
Hyaline cartilagearticular cartilage, airways, larynx, trachea, bronchi, rib cartilage
isogenous
group
capsular matrix
perichondrium
teritorial matrix
interteritorial matrix
Growth of cartilage: interstitial and appositional
Hyaline cartilage - matrix
type II collagen fibrils, hyaluronan, proteoglycans (aggrecan),
fibronectin, tenascin
Elastic cartilageexternal ear, auditory (Eustachian) tube, epiglottis, larynx
perichondrium
elastic
fibers
haematoxylin - eosin
orcein
Fibrocartilage - no surrounding perichondrium,
resilient and resistent,
(intervertebral discs,
symphysis ossis pubis,
menisci in joints)
Chondrocytes- singular, in
rows or in small isogenous
groups
ECM – abundant collagen fibres
(type I collagen) and fibrils
(type II collagen), considerably
less amorphous matrix
(proteoglycan versican)
azan staining