Bone and Bone Development Flashcards
2 ways to visualize
• Ground bone = unpreserved bone is ground down so thin light can pass ____
– ____ & ____ matrix do not survive, but general architecture (____, lacunae, ____ {narrow tunnels}) are visualized
• ____ bone = cells are fixed and inorganic matrix is removed by decalcification
– Good detail of ____ material
through cells organic matrix lamellae canaliculi decalcified organic
Bone is a connective tissue. Types: • \_\_\_\_ connective tissue – Mesenchyme (stem cells!) – Mucous • Connective Tissue Proper – \_\_\_\_ – \_\_\_\_ • Specialized connective tissue – Cartilage – \_\_\_\_ – Hematopoetic
embryonic
loose
dense
bone
Bone is a ____ connective tissue
What is connective tissue made of?
• Extracellular matrix
– Fibers = proteins made of long peptide chains
produced by fibroblasts (____!)
– ____ substance = gel-like matrix where cells and fibers are embedded
• Cells
– Mesenchymal stem cells form:
– Osteoprogenitor cells
– Osteoblasts, Fibroblasts, Chondroblasts, Myofibroblasts, Adipose cells
– ____, mast cells & basophils
– ____, plasma cells, eosinophils, monocytes & ____
specialized
collagen
ground
macrophages
lymphocytes
neutrophils
Classification of Bone
• Compact/dense forms ____
• ____ forms inside consists of trabeculae
– Spaces within have marrow & blood vessels
• Woven = ____ (Immature bone)
• More ____ per unit of area & cells are ____ arranged, More ____
- Lamellar (Mature bone)
- ____ arrangement of collagen fibers
outside spongy/cancellous non-lamellar cells randomly ground substance
regular
Bone Classification (cont’d)
- Bone tissue
- –by ____
- –(trabecular = spongy = cancellous, ____ = ____ = compact)
— by stage in formation
(primary = ____/____, scondary = ____/____)
architecture
cortical
dense
woven/immature
lamellar/mature
Bone develops in two ways from mesenchymal stem cells:
- endochondral ossification from a ____ precursor
- intramembranous ossification directly from ____
Immature bone matrix formed by either process looks the ____
Facial bones arise from ____
hyaline cartilage
mesenchyme
same
intramembranous
Bone matrix is formed by Osteoblasts
Osteoblasts are derived from
____
(have potential to ____ and capacity to ____)
These cells arise from ____ mesenchymal stem cells that can become fibroblasts, osteoblasts, adipocytes, chondrocytes or muscle cells.
Found on the ____ and ____ of bones. Look flattened and ____ with elongate or ovoid nuclei.
osteoprogenitor stem cells
proliferate
differentiate
multipotent
external (periosteum)
internal surface (endosteum)
squamous
Mesenchymal Stem Cells:
Give rise to ____ cells, but can also form fibroblasts, chondroblasts, adipocytes and muscle cells.
Osteoblasts: derived from osteoprogenitor cells
secrete ____ then form osteocytes.
Osteoblast formation is controlled by members of the ____
osteoprogenitor
bone matrix (osteoid)
bone morphogenetic protein family
Difficult to differentiate ____ from osteocytes histologically
Mesenchymal stem cells sittwithin the connective tissue; induced to form OPC, which are then ____ to giving rise to osteoblasts
progenitor cells
committed
Bone formation by osteoblasts
Four step process:
1. ____ deposition
forms a collagen (mainly ____) fibril matrix like steel bars in concrete
- secretion of ____
amorphous matrix of GAGs, PGs, glycoproteins, salt and water. ____ is the combination of steps 1 and 2 - ____ seeding
osteoblasts saturate ground sustance with ____ and phosphate which precipitate as ____ crystals - mineralization and ____
calcium phosphate crystals are modified to form ____
crystals tethered to collagen by ____, this provides strength for the bone
collage
type I
ground substance
osteoid
crystal
calcium
calcium phosphate
maturation
hydroxyapatite
proteoglycans
Components of the bone matrix
(Osteoid)
____% organic, ____% inorganic
Organic: Fibers: \_\_\_\_ collagen Ground substance: previous slide Non Collagenous proteins: Important! 1. \_\_\_\_ a ligand to induce formation of osteoclasts 2. \_\_\_\_ stimulating factor (M-CSF) 3. \_\_\_\_ 4. \_\_\_\_
Inorganic:
Calcium phosphate deposits with crystalline characteristics of ____.
35 65 type I RANKL macrophage colony osteoprotegrin osteopontin hydroxyapatite
Osteocytes: Are osteoblasts that became trapped in ____
Maintain ____ quality
Transmit ____ signals
Linked by ____ to each other and to bone lining cells
Periosteal and Endosteal cells: ____ Osteoblasts
matrix bone mechanical gap junctions inactive
Cannot distinguish between ____ and ____
Osteoblasts are larger and more ____
OPC
endosteal cells
cuboidal
Osteocyte • Completely surrounded by bone matrix • Maintain \_\_\_\_ homeostasis • \_\_\_\_ is the space this cell inhabits • Cytoplasmic processes in canaliculi are linked by \_\_\_\_ • States – \_\_\_\_ – Formative deposits matrix – Resorptive- has \_\_\_\_
• ____ than osteoblast precurser and usually highly distorted by ____ in routine preps
calcium lacuna gap junctions quiescent lysosomes smaller shrinkage
Bone-lining cells: Periosteal and endosteal cells
• Derived from ____
• Cover bone that is not ____
• Flat cells with few ____, have ____ join processes of adjacent cells
• Function in maintenance and nutritional support of ____ in underlying bone
osteoblasts remodeling organelles gap junctions osteocytes
