Summary of Junqueira: Histology of the Bone with additional material from Netter's, DeFiore's and Weiss' Atlases. Includes abridged but detailed explanation of key points with Electron Microscopy, H&E, Immunohistochemistry and Diagrams.
02 connective tissue histology notes to 31 slides / images Class notes MTY1204 (histology) Junqueira's Basic Histology: Text and Atlas, Fiifteenth Edition, ISBN: 9781260026177
05 bone histology 39 notes to slides / images Class notes MTY1204 (histology) Junqueira's Basic Histology: Text and Atlas, Fiifteenth Edition, ISBN: 9781260026177
Immune System & Lymphoid Organs
Alles voor dit studieboek
(16)
Geschreven voor
David Tvildiani Medical University
Histology
Alle documenten voor dit vak (7)
Verkoper
Volgen
galadashvili
Ontvangen beoordelingen
Voorbeeld van de inhoud
Bone is the main constituent of the adult skeleton.
• It confers mechanical and metabolic functions to the
skeleton • Histological examination of bone
• It is classified as a specialized connective tissue required decalcification before paraffin
composed of:
or plastic fixation followed by a
◦ Calcified Extracellular Material: Bone Matrix
◦ Three Major Cells Comprising Bone: specialized microtome sectioning
‣ Osteocytes: Found in Lacunar Cavities between
Lamellar Bones with Cytoplasmic Processes extending through canaliculi to
make contact with vessels
‣ Osteoblasts: synthesize organic components of the bone matrix
‣ Osteoclasts: multinucleate giants cells involved in bone resorption and
remodeling
• Bone are lined with layer of connective tissue containing osteogenic cells:
◦ Endosteum on the inner surface surrounding marrow cavity
◦ Periosteum on the external surface
OSTEOBLAST
• Located on the Surface of the Bone Matrix
◦ Secretes the Organic Components of not yet calcified Osteoid:
‣ Type I Collagen
‣ Proteoglycans
‣ Glycoproteins
◦ In addition they produce:
‣ Macrophage Colony Stimulate Factor(M-CSF)
‣ Receptor for activation of Nuclear Factor Kappa B(RANKL)
‣ Osteoprotegerin
‣ Osteocalcin(for bone mineralization)
‣ Osteopontin(sealant)
‣ Sialoprotein(binding of osteoblasts to extracellular matrix)
• They Resemble Simple Cuboidal Epithelium.
◦ Cuboidal/Columnar: Active, Intensely Basophilic
‣ Active Cells have prominent RER and Golgi Complex with secretory vesicles
◦ Flat: Inactive, less Basophilic(Mainly Bone Lining Cells of Endosteum and
Periosteum)
• Osteoblasts extend cytoplasmic processes through the osteoid which connect them to
neighboring osteoblasts via gap junctions.
• Osteoblasts contain receptors for PTH, Estrogen and Progesterone.
• Osteoid Calcification:
◦ Osteoblasts release:
‣ Vit-K Dependent Osteocalcin which binds Ca+
‣ Matrix Vesicles rich in Phosphate PO4- and Alkaline Phosphatases which
hydrolyze the alkali phosphate
• These ions form as a foci for the formation of Hydroxyapatite
[Ca10(PO4)6(OH)2] which serves are the bases of calcification by
accretion of more ionic minerals.
• Osteoblasts surrounded by osteoid are called Osteocytes.
OSTEOCYTE
• Flat Almond Shaped Cells with few RER, Golgi, and Clumped up Chromatin
• High Nucleus to Cytoplasm ration.
• They are:
◦ Located Between Lamella
◦ Enclosed in Lacunae and bathed in extracellular fluid.
◦ Have Cytoplasmic Processes that extend through canaliculi and make contact with
blood vessels and other osteocyte processes via gap junctions.
• Their Function:
◦ Maintenance of Bone Matrix
‣ Production of proteins such as Sclerostin
‣ Production of Cytokines that regulate bone remodeling
‣ Calcium Homeostasis via exchange with extracellular fluid through Osteocytic
osteolysis.
‣ Sensors for detection of bone stress
OSTEOCLAST
• Osteoblasts under stimulation of Para-thyroid Hormone(PTH) produce two polypeptides,
Monocyte/Macrophage Colony Stimulating Factor(M-CSF) and Nuclear Factor κB Ligand
(RANKL) which stimulate the differentiation and activation of Osteoclasts
• Osteoblasts can also prevent the activation of Osteoclasts by secreting
Osteoprotegerin which acts as a decoy ligand for RANK.
, • Calcitonin can also prevent osteoclast activation.
• Osteoclasts are large multinucleated(~50), motile cells that perform the function of
matrix resorption and remodeling and are derived from monocytes.
◦ Osteoclasts are eosinophilic
◦ They lie within resorption to Howship Lacunae/cavities
◦ They form sealed junctions via Osteopontin with Ruffled Borders(allows for
adhesion with matrix) secrete
‣ Collagenase
‣ Cathepsin K
‣ Proton Pump--> Make environment acidic
in order to break down the Hydroxyapatite and promote digestion of matrix
proteins.
BONE MATRIX
• Inorganic Components:
◦ Hydroxyapatite Crystals [Ca₁₀(PO₄)₆(OH)₂] composed of:
‣ Calcium Phosphate
‣ Magnesium
‣ Bicarbonate
‣ Potassium
‣ Citrate
‣ Sodium Ion
• Organic Components:
◦ Type I Collagen(95%)
◦ Very small amount of Type IV Collagen
◦ Proteoglycans:
‣ Chondroitin Sulfate
‣ Keratin Sulfate
‣ Hyaluronic Acid
◦ Glycoproteins
‣ Osteonectin- influences the calcification of bone by
binding calcium and Type I collagen in the bone matrix
‣ Osteocalcin
‣ Osteopontin
◦ Sialoprotein- adheres bone cells to bone matrix
PERIOSTEUM and ENDOSTEUM
• Periosteum is a connective tissue layer that covers the bone
on its surface with the exception of articulating synovial
surfaces and where muscles attach.
◦ Composition:
‣ Outer Dense Connective Tissue layer with Type I
Collagen Perforating/Sharpey Fibers attach periosteum
to the bone matrix as well as blood vessels, nerves
and lymphatics
‣ Inner Osteogenic layer(Cambium) which contains Osteoprogenitor Cells for
Appositional Growth
• Endosteum is a specialized connective tissue layer which lines the farrow cavities
and supplies osteoprogenitor cells and osteoblasts for bone growth and repair.
TYPES OF BONES
Voordelen van het kopen van samenvattingen bij Stuvia op een rij:
Verzekerd van kwaliteit door reviews
Stuvia-klanten hebben meer dan 700.000 samenvattingen beoordeeld. Zo weet je zeker dat je de beste documenten koopt!
Snel en makkelijk kopen
Je betaalt supersnel en eenmalig met iDeal, creditcard of Stuvia-tegoed voor de samenvatting. Zonder lidmaatschap.
Focus op de essentie
Samenvattingen worden geschreven voor en door anderen. Daarom zijn de samenvattingen altijd betrouwbaar en actueel. Zo kom je snel tot de kern!
Veelgestelde vragen
Wat krijg ik als ik dit document koop?
Je krijgt een PDF, die direct beschikbaar is na je aankoop. Het gekochte document is altijd, overal en oneindig toegankelijk via je profiel.
Tevredenheidsgarantie: hoe werkt dat?
Onze tevredenheidsgarantie zorgt ervoor dat je altijd een studiedocument vindt dat goed bij je past. Je vult een formulier in en onze klantenservice regelt de rest.
Van wie koop ik deze samenvatting?
Stuvia is een marktplaats, je koop dit document dus niet van ons, maar van verkoper galadashvili. Stuvia faciliteert de betaling aan de verkoper.
Zit ik meteen vast aan een abonnement?
Nee, je koopt alleen deze samenvatting voor €2,94. Je zit daarna nergens aan vast.
