Term
| 5 steps for prepping tissues |
|
Definition
1. fixation
2. embedding
3. sectioning
4. staining
5. microscopy |
|
|
Term
|
Definition
Kill microorganisms, freeze tiss in timeso less degradation taking place.
Usually formalin, formaldehyde; could also use alcohols to penetrate tiss faster than aldehydes. Store tiss at cold temp
Chemicals can often make tissues easy to manipulate b/c they become harder |
|
|
Term
|
Definition
Preparing soln in paraffin wax sometimes paired w/ xylene to remove alcohols or epoxy (TEM)
Surrounds tiss in firm substance so it is stabile and doesnt fall apart
Helps w/ slicing tiss thin |
|
|
Term
|
Definition
| Uses a microtome to prepare small sections |
|
|
Term
|
Definition
| Allow to see the diff components of cell |
|
|
Term
|
Definition
*H&E (hematoxylin and eosin )
Basophilic or eosinophilic
*toluidine blue
aqueous dye. need to pair w/ lipophilic dye if you wan to see lipids
*heavy metals
Uranium, lead
Chromatin and protein very e- dense so bind to these
**For carbohydrate and lipid rich structures, use special stains (cryosection and lipophilic dyes) |
|
|
Term
|
Definition
hematoxylin and eosin
stain basic substances. Basic dyes have a + charge;
*Dna, rna proteoglycans and special proteins
*Whether the cytosol contains obvious basophilic staining will vary, depending on the ribosome component and arrangement (i.e. the rRNA).
*Small RNAs like mRNA and tRNA and non-coding RNAs are never in large enough clusters in the cytoplasm to be seen with the LM. |
|
|
Term
|
Definition
stain acidic structures.
Most proteins, and protein rich organelles (mito, collagen, cytoskeleton) |
|
|
Term
|
Definition
|
|
Term
|
Definition
Epithelial
CT
Muscle Tissue
Nerve Tissue |
|
|
Term
| Epithelial (cells, matrix, func) |
|
Definition
Aggregated, polyhedral cell
Small amount
Line and cover surf and cavities, forms glands |
|
|
Term
|
Definition
Various, fixed and transient
extensive
Underlies and supports other tiss
Specialized func |
|
|
Term
| Muscle Tiss (cells, matrix, func) |
|
Definition
Elongated and contractile
moderate
Strong contraction for body movements.
Motility of contents |
|
|
Term
| Nerve Tiss (cells, matrix, func) |
|
Definition
elongated
Very sparse
Receives, transmits, and integrate info
Coordinates activity |
|
|
Term
|
Definition
*avascular
*Aggregate polyhedral cells, w/ minimal intercellular space
This is b/c they need to form tight junc w/ e.other, again from selective diffusion and barrier reasons
*APICAL SURF- top, can have specializations
*BASAL SURF- bottom, attached to CT |
|
|
Term
|
Definition
Maintains barriers via:
Chemical separation
Selective diffusion/absorption
Physical separation
Protective barrier (skin) |
|
|
Term
|
Definition
allow for mechanical, chemical and electrical coupling and forming tiss groups through...
1) Barrier between compartments
Polarizes the epithelial layer and facilitates transport
2) Cell to cell adhesion
Aids in barrier and protective func b.c it is tightly bound
3) Cell-cell communication
Coordinates functional aspects and allows cells to work in unison
4) Cell to basal lamina adhesion
Anchors epithelium to underlying tissue (secured in place) |
|
|
Term
|
Definition
3 junc working in conjunction w/ each other; Junc can occlude, anchor, and/or communicate
(1) tight junc
(2) adherence junc
(3) desmosome |
|
|
Term
| Tight junc (location, type, func, proteins) |
|
Definition
TIGHT(zonula occludens)
Closer to apical surf (1st b/c needs to be tightest to prevent leak)
Cell-cell junc
* involved in intertwining sheaths at apical surf
*seals off the upper part of epithelium to prevent leakage from lumen into epithelial space and vice versa
Claudin and occludin |
|
|
Term
| Adherence junc (location, type, func, proteins) |
|
Definition
ADHERENCE (zona adherens)
Middle junc
Cell-cell junc
*cadherin bids to microfilaments (F actin and myosin) in cytosol
Cadherin |
|
|
Term
| Desmosomes (location, type, func, proteins) |
|
Definition
DESMOSOMES(macula adherens)
Lowest most connection
Cell- cell junc
*cadherin blinds to intermediate filament
*well developed in surf of skin
cadherin |
|
|
Term
| junc that attach basement meb of the epithelial cell to the extracellular matrix (ECM) |
|
Definition
hemidesmosomes
focal adhesions |
|
|
Term
| hemidesmosomes (location, type, func, proteins) |
|
Definition
*basal and basolateral
not lateral, so not involved in cell-cell-connections)
Cell-basement memb/ ECM junc
* will bind to intermediate filament to hold basement memb in place
Integrin
*Receptors for different proteins in basement memb so will bind and hold it in place |
|
|
Term
| focal adhesions location, type, func, proteins) |
|
Definition
* on basal surf
Cell-basement memb junc
* intermediate filament
integrin |
|
|
Term
| Epithelial specializations |
|
Definition
microvilli
cilia
interdigitations |
|
|
Term
|
Definition
*finger -like projections from apical surface of epithelial cells
*Core of actin microfilaments → provides support
Actin is eosinophilic so stains more pink
*Non-motile → increase SA for absorption
*Will be present in epithelial cells that our specialized for absorption |
|
|
Term
|
Definition
*Finger-like projections from apical surface of epithelial cells
*Microtubules that have polarization and proteins
*Core of tubulin microtubules and associated motor proteins
*Motile → unidirectional beating moves material along apical surf, or movies fluid in compartment
*movement allows for hlp with passage of substances. Usually with cells involved in secretion (but not necessarily doing the secretion, sometimes find goblet cells do secreting)
*Cilia will be found in cells that need movement
EX: epithelial tissue of lungs → used to move fluid toward mouth
EX: goblet cells → secreting cells to move mucous |
|
|
Term
|
Definition
*Found on lateral and basal surf of epithelium
*Specialized for absorption/transport (Ex: gut, kidney,)
Interdigitations- allows for transport between cells. And also for absorption.
*Inc SA for transport proteins (Ex: Na+/K+ ATPase) out and in
There are lots of pumps along the surface of the digitations themselves
*Can be found in cells that are important in absorption (ex: gut) |
|
|
Term
| 2 major types of epithelia |
|
Definition
1) Surface epithelia
*Lining the outer or inner surf of organs
2)Glandular epithelia
* Epithelia that makes glands and is involved in secretion |
|
|
Term
| Classification of surface epithelia |
|
Definition
Surface epithelia can be classified in multiple ways:
1)Number of cell layers
simple, strat, pseudostrat
2)Cell shape
squamos, cuboidal, columnar, transitional
3)Surface specializations
cilia, microvili, keratin |
|
|
Term
| Classification by cell layers |
|
Definition
SIMPLE
One layer of cells
STRATIFIED
Multiple layers of cells
PSEUDOSTRATIFIED
Single layer of cells w/ all cells attached to basal lamina
Nuclei are at more than 1 level
Kinda look like stratified epithelium but only have one layer of cells. Tricky b/c it looks like multiple layers
ONLY found w/ columnar type epithelium |
|
|
Term
| Classification by cell shape |
|
Definition
SQUAMOUS
Flat; tile-like
Nuclei typically looks bigger than cytosol
Usually lining lumen of blood vessels and organ cavities (ie pleural cavity)
CUBOIDAL
Square in section; height ≈ width
Usually uniform shape
COLUMNAR
tall in section; height > width
TRANSITIONAL
Variable cell shape; specialized
EX: found in bladder
all of the cells make contact w/ basement memb (so kind of similar to pseudostratified). Ones at the top look like little pillows. But cells are not all in same state. This arrangement allows for extension ( example bladder, when emptying out cells look more flatter)
NOTE: for stratified epithelium, classification refers only to the surface layer of cells. So you name it by what is at the uppermost surface |
|
|
Term
| Classification by surface specializations |
|
Definition
CILIA
Movement of material along the free surface
MICROVILLI
Increase surface area (aka brush or striated border)
KERATIN
Layers of dead cells designed to provide physical protection
dead layers that lost nuclei and acting a a protective hard surface
ONLY STRATIFIED SQUAMOUS EPI |
|
|
Term
|
Definition
aggregations of secretory epithelium (occasionally single cells)
** all glands are made of epithelial cells, but not all epithelial cells are found in glands ** |
|
|
Term
|
Definition
have duct(s) that empties product into cavity/surface (lumen) some are used for secretory, other excretory.
Formed by infoldings of lining epithelia that becomes specialized for secretion, since the ducts maintain connection w/ initial epithelium, they empty the secretory product directly into the cavity/surface;
every exocrine gland has a duct |
|
|
Term
|
Definition
| lack duct(s) product released and taken up into circulation (for another lecture) |
|
|
Term
| Classification of exocrine glands |
|
Definition
1)Morphology (structure) of DUCTS
SIMPLE GLAND
COMPOUND GLAND
2)Morphology (structure) of SECRETORY PORTIONS
TUBULAR GLAND
ACINAR GLAND
BOTH
3)Mode of secretion
MEROCRINE
HOLOCRINE
APOCRINE
4)Type of secretion (only applies to merocrine glands)
Serous
Mucous
Mixed (sero-mucous) |
|
|
Term
|
Definition
| duct that is unbranched; can be long, short, straight, twisted |
|
|
Term
|
Definition
if duct is branched; the larger the compound gland, the more elaborate the system
Branched ducts converging into common duct;
usually seen as multiple sections through tubes of variable height epithelium w/ obvius lumen
Classified by structure of secretory component
Much lrger than simple glands |
|
|
Term
|
Definition
cells arranged in tubular structure
more oval shaped |
|
|
Term
|
Definition
rounded clusters of cells
are more spherical |
|
|
Term
|
Definition
| functional unit of compound glands (ducts + secretory units) |
|
|
Term
|
Definition
| supportive CT (CT capsule + supportive framework) → capsule made up of collagen, elastic and reticular fibers (discussed more in next lecture) |
|
|
Term
|
Definition
*standard exocytosis
secretory vesicle is going to fuse with cell wall and secrete products (main form of secretion)
*protein, mucous, aqueous secretion
*most common type
EX: salivary glands
So will stain eosinophilic (hot pink areas)
This mode it best for protein and carbohydrate (soluble);
Merocrine secretions can be produced by simple and by compound glands |
|
|
Term
|
Definition
Some glands make lipid rich secretions that cannot be secreted by merocrine:
*product is whole degenerated cells
Accumate lipid in secretory cells and die off and become secretory
*due to apoptotic cell death
(secretory cells dying off and the debri is released as the secretory product)
*only sebaceous glands of skin and similar
EX: sebaceous glands |
|
|
Term
|
Definition
Some glands make lipid rich secretions that cannot be secreted by merocrine:
*pinching off fragmenmts from cell surf
glands w/ secretory cells that pinch off lipid rich regions of cytoplasm and release them from apical surf
Pinched off vesicle is what gets released into the duct
*Actual loss of the memb w/ exocytosis,
*rare
EX: mammary gland |
|
|
Term
|
Definition
*Specialized cells found in most glands especially prominent in apocrine glands
Poses characteristics of both musc and epitheleal cells (some actin and myosin filaments) → so when stimulated, cells will contract and stimulate release of products
*Have molecular feat of musc AND epithelial cells (contractile func and found at base of epithelium (inside BM)
Make sense b/c when they contract it will help push the product out
*Stain eosinophilic (probably b/c of actin) |
|
|
Term
|
Definition
often protein rich amd/or watery
EX: salivary glands
Very protein rich so will see very eosinophilic in staining (pink) |
|
|
Term
|
Definition
carbohydrate rich/sticky
EX: protective coating of hollow organs
Will have carbohydrates (water soluble) → so gets lots usually during fixing/staining |
|
|
Term
|
Definition
both serous and mucous, made by different cells in same gland; ONLY in compound glands
Each cell can only make one type of secretion but you can have more than one cell in secretory unit
Can create serous demilunes (ONLY PRESENT IN MEROCRINE) |
|
|
Term
|
Definition
Serous secreting cells present in secretory unit of mucous cells as well as
Mucous secreting cells are pushing serous secreting cells to one end --> forms crescent shape
Demilunes are very eosinophilic b/c they contain serous-secreting cells. BUT they are getting pushed to the periphery by the mucous secreting cells (in mixed-gland situation) |
|
|
Term
| SMALL (INTERCALATED) DUCT |
|
Definition
non secretory duct
Connects secretory unit to striated ducts |
|
|
Term
|
Definition
| Not a secretory duct but has secretory properties can tell b/c mitochondria has striated appearance) |
|
|
Term
|
Definition
*A special case of ‘simple’ gland
*Single cell gland which secretes mucus
*Can be security cell of other types of glands (ex: simple tubular)
*Can also be found in isolation (single cell gland
*Secretes mucus to free surface, the cell itself is a gland
*Releases mucin in the epithelial surface
*Will push nucleus down to basement portion of cell to secrete
*Will appreciate an absence of stain b/c mucigen is very carbohydrate rich, so it does not stain well |
|
|
Term
|
Definition
| Physical and chemical support of other tissues and organs |
|
|
Term
|
Definition
around/between other tissue types (connects things)
Underlies epithelial and surround musc and nervous tiss
Provides a framework for support and connections
Cells DO NOT form junc w/ each other
ECM usually most abundant component
ECM usually gives the tissue its characteristic properties
Conduit for blood vessels and nerves
Has bv and nerves running through it (unlike epithelial cells who do not have vascularization) |
|
|
Term
|
Definition
CT is composed of EXTRACELLULAR MATRIX (ECM) which contains:
1)Fibers
Proteins that polymerize into long or short fibrils and fibers
Primarily fibronectin, collagen (many types), and elastin
Presence of proteins make them eosinophilic (pink)
2)Ground substance
‘Hydrated space’ consisting of multiple proteins
Glyco proteins
Proteoglycans
Glycosaminoglycans (ex: hyaluronan- polymers of modified sugar residues)
Acts as a hydrated gel and provides resiliency
*fibers + ground substance collectively give CT its major functional properties * |
|
|
Term
|
Definition
1) Resident fixed cells
Synth and maintain ECM
Fibroblasts and members of ‘fibroblast’ family
Fibroblasts, adipose cells, smooth musc cells, chondrocytes, osteocytes
2) Transient cells
Bone marrow derived, immune cyst cells
Cells of the immune cyst (Leukocytes)
Involved in immune surveillance and defense
So they travel through and reside in the tiss, but do not contribute to formation
Secondarily take up residence in CT (ex: macrophages) and/or traffic between CT and immune organs (ex: lymphocytes) |
|
|
Term
|
Definition
|
|
Term
|
Definition
ABUNDANCE: ~90% of CT fibers
FUNC: tensile strength (can withstand a lot of force, but not good for stretching)
Reason why they are bundled
STAINING: very eosinophilic; most fibers we will see in LM will be collagen
The bundle of fibrils of the collagen fiber is what is visible in LM. cannot see e. Individual fibril in LM, but can see it in TEM
CHARACTERISTICS:
protein fibers that make long straight fibers (ex: tendons- fibre bundles in irregular CT) and meshworks (ex: basal lamina)
Whole proteoglycan molecule is all triple helix
OTHER: makes longest/largest and strongest fibers of body |
|
|
Term
|
Definition
ABUNDANCE: ~10% of CT fibers; higher in some CT
FUNC: stretch and recoil
When fiber is stretched, the coils straighten but molecules dont pull apart. Recoil upon release of stretch
Randomly coiled together but linked strongly by covalent bonds so can stretch and recoil w/out tearin bonds apart
STAINING: poorly eosinophilic; light refractile; special stains are needed to catch it
CHARACTERISTICS:
Random coiled elastin molecules attached covalently together
OTHER: produced by fibroblasts and vascular smooth musc cells
Will find them in ear pinna, vocal cords, epiglottis, lungs |
|
|
Term
| ECM Ground substance (components) |
|
Definition
Water (60-90%)
Carbohydrate polymers
Glycosaminoglycans (GAG)
- charge polysaccharide compounds (stains poorly, usually colorless or faint blue)
Proteoglycans (PG)
Also stain poorly unless in high concentrations
Multiple other soluble proteins and glycoproteins
including fibronectin, laminin, growth factors, etc |
|
|
Term
| ECM Ground substance (func) |
|
Definition
Provides turgor pressure (resistance to compression)
Allows cells to not get squished
Occupies a lrg volume and resists compression bc of bound water
Can be watery (eg: loose CT) to very thick gel (ex: cartilage) depending on GAG conc
Gels inhibit cell movement depending on amounts of GAGs
Water in gels is the medium for diffusion through CT |
|
|
Term
| ECM Ground substance (staining) |
|
Definition
Stains poorly w/ H&E (colorless to light blue)
PG and GAGs carry net - charge (so they bind water and basophilic dyes) |
|
|
Term
|
Definition
1) FIBROUS CT (OR CT PROPER)
Loose CT
Dense Irregular CT
Dense Regular CT
2) SPECIALIZED CT
Adipose Tissue
Cartilage
Bone
Blood |
|
|
Term
|
Definition
Abundant ground substance, few fibers
Small collagen fiber bundles (often not seen in LM)
Often very cellular (cells more numerous in loose than in dense)
will be directly below epithelium and provide vascularization and support. Most widely distributed type. Cells and fibers are widely separated by spaces and filled w/ ground subs |
|
|
Term
|
Definition
RETICULAR CT
*Collagen type III fibers form 3D network
*Found only in lymphoid organs where it forms scaffold to support immune system cells
*Very thin and stain poorly w/ H&E |
|
|
Term
|
Definition
Abundant fibers, mostly collagen type I
Lrg/prominent fiber bundles, few cells, little ground substance |
|
|
Term
|
Definition
DENSE IRREGULAR CT
*Collagen bundles randomly oriented
-Allows for tiss to adapt to changes in size of organ and stretching forces in any direction
-EX: digeest syst, lung capsule, liver and kidney, joint capsules
*fiber bundles lrg, less ground subs, and cells. Cells present will be fibroblasts mostly. Collagen fibers arranged in various angles
DENSE REGULAR CT
*Collagen bundles in regular (aligned) orientation
-Will have a pattern of alignment
-Fibers arranged in same directions
found in ligaments and tendons
-Increases the tensile strength w/ this config |
|
|
Term
|
Definition
Adipocytes (fat cells) frequently found as single cells or in small groups in loose CT
Also form lrg masses = adipose tissues
Differentiate from mesenchymal/fibroblast like precursor cells
Adipose tiss is highly cellular, unlike most CT
-Act as thermal and mechanical insulator (tensile strength of adipose tissue)
-EX: K9 foot pads |
|
|
Term
|
Definition
UNLICOULAR (white)
*triglycerides in a SINGLE droplet
*rim of cytoplasm w/ flattened nucleus
* E in homeostasis and hormone secretion
-leptin, steroid hormones, etc
*padding and insulation when lrg #s
MULTILOCULAR (brown)
*triglycerides in MULTIPLE droplets
*round nucleus
*obvious cytoplasm w/ lots of mitochondria
*lipid metabolized in cell for heat production |
|
|
Term
|
Definition
*Reisists mechanical stress, absorbs shock, slides on surfaces (considerable tensile strength)
*Avascular: limits size→ poor capacity for repair
*Cartilage is Generally made up collagen 2 (generally looser) except in fibrocolalgen that will be made up with collagen type 1
*Can be distinguished by the consistency of ground subs → high presence of GAGs, very dense, not watery |
|
|
Term
|
Definition
Supports soft tiss
Facilitates bne movements
Guides bone development |
|
|
Term
|
Definition
Articular surfaces of bones
-sliding and friction protection
Ears and nose
Airways and lungs
Growth plate of bones |
|
|
Term
|
Definition
FIBROBLAST-LIKE CELLS
*edge of cartilage- form a dense CT layer (perichondrium)
-not found in all types of cart
*proliferate to produce chondroblasts
CHONDROBLASTS
*act as progenitors
*proliferate/differentiate to chondrocytes
CHONDROCYTES
*mature cart cells
*produce and are trapped in ECM
*reside in lacuna
**cytoplasm in chondrocytes is basophilic b/c of lrg quantities of RER (blue or purple)
**chondrocytes are a less active cell that chondrocytes, but still maintain ECM |
|
|
Term
|
Definition
Hyaline Cart
Elastic Cart
Fibrocartilage |
|
|
Term
| Hyaline Cart (ECM components, perichondrium, location) |
|
Definition
*mainly collagen type II
*GAGs, PGs, etc
*yes, except surf joints
*resp tract, bone articulations, growth plate, fetal skeleton |
|
|
Term
| Elastic Cart (ECM components, perichondrium, location) |
|
Definition
*mainly collagen type II
*GAGs, PGs, etc
*elastin fibers
*yes
*ear (external and internal)
*epiglottis and parts of pharynx |
|
|
Term
| Fibrocart (ECM components, perichondrium, location) |
|
Definition
*hyaline cart-like regions
*dense CT regions rich in collagen type I, b/c more dense
*no
*IVD
*pubic symphisi and some other joints
*meniscus
*insertions and tendons |
|
|
Term
|
Definition
*CT cells embedded in lacuna in matrix (similar to cartilage)
*Osteocytes
*Matrix has little ground substance but extensive collagen (primarily type 1)
*Matrix is mineralized
*Tiss is highly vasculariszed→ excellent repair capabilities
*Can form very lrg skeletal structures |
|
|
Term
|
Definition
*Solid support for body
*Protect vital organs
*Harbors one marrow (hematopoiesis- blood generation in bone marrow)
*Acts as mineral and ion reservoir
*Transforms musc contraction to body movement |
|
|
Term
|
Definition
SPONGY (CANCELLOUS/ TRABECULAR) BONE
Boney meshwork consisting of trabeculae
forms interior of bone
COMPACT (DENSE) BONE
Dense latter that forms the outside of bones |
|
|
Term
|
Definition
*Both tissues cannot be paraffin embedded and sectioned until minerals are leached out, leaving organic material behind (cannot be fixed w/ formalin)
*LACUNA- space for osteocytes in growing bone will form here. Their organization allows for bone growth
Can also find LACUNA in CT for chondrocytes |
|
|
Term
| Mineralized vs demineralized bone |
|
Definition
Demineralized bone:
*Removes minerals from bone → shows cellular artfacts
*But reveals arrangement of collagen layers (lamellae of osteoid)
*Very eosinophilic b/c collagen type I, can appreciate the parallel layers
Mineralized bone:
*Needs to be Sliced very thin to be transparent
*No cells left, but see fine structure of bony spaces |
|
|
Term
|
Definition
| cylindrical unit of compact bone |
|
|
Term
|
Definition
principle cell in mature bone) are trapped in lacunae between lamellae
Note how lamella forms in intrinsic circles
Osteocytes have gap junc between connection points → allows for communication between osteocytes |
|
|
Term
| Central osteonal (haversian) canal |
|
Definition
runs along length of osteon, carrying blood vessels and nerves
*Osteonal canals lined by bone lining cells and osteoprogenitor cells (endosteum)
*Osteon will have multiple lamella, w/ multiple lacunae, w/ mult osteocytes |
|
|
Term
|
Definition
Fine tunnel-like spaces (canaliculi) cross lamellae
Carry osteocyte processes
Connect to cells in endosteum and osteocanals
Different osteocytes from different lamella can make contact w/ each other → allows them to connect |
|
|
Term
|
Definition
between lamellae
Walls of lacunae are covers in GAG proteins |
|
|
Term
|
Definition
| Woven bone (immature bone) will eventually (through destruction and redeposition) become Lamellar bone which consists of compact bone and cancellous bone |
|
|
Term
|
Definition
*Random disposition of collagen fibers and osteocytes
*1st bone tissue to appear during development and fx repair
*Temporary; replaced by lamellar bone w/ fwe exceptions (ex: tendon insertions, alveolar sockets of teeth)
*Is rapidly produced but not as strong as lamellar bone
*Immature bone and also involved in repair (new bone)
*Woven bone, things are not organized in a organized, parallel fashion as in lamellar bone |
|
|
Term
|
Definition
*Collagen fibers organized in parallel within each lamella of calcified matrix
*Collagen fibers oriented in different directions in adjacent lamellae
*Majority of bone tiss in adult, whether compact or cancellous (spongy) |
|
|
Term
| converting woven to lamellar |
|
Definition
1) osteoclasts play key role in this conversion and in ongoing bone remodeling
-Osteoclasts act like a specialized macrophage for bone (break down bone tissue which allows for new growth)
-Osteocytes die and osteoclasts come in and eat dead bone tissue, this is how we know they're important
2)Osteoclasts formed by fusion of several monocytes
-Monocyte- multinucleated (big hint when looking in lab), motile and very large cell.
3)Attach to surface of bone along the outside edge of cell, sealing of basal compartment
4) Secret acid into the space within the seal
-Mineralization dissolves to create a resoprition cavity
5) Release lysosomal vesicles that digest matrix proteins
Released mineral absorbed into circulation |
|
|
Term
|
Definition
1) INTRAMEMBRANOUS OSSIFICATION
*Bone forms directly from CT
*For most flat bones (skull, mandible, scapula)
*Takes place w/in condensations of embryonic mesenchymal tissue
2) ENDOCHONDRAL OSSIFICATION
*Involves a cart precursor cell
*Bone matrix deposition occurs on an existing cart model
-Cart is becoming bone. Bone growth occurring on top of he cart
*Used to generate most bones, used for growth (elongation) of long bones
Growth in width = intramembranous ossification
Growth in length = endochondral ossification |
|
|
Term
| INTRAMEMBRANOUS OSSIFICATION |
|
Definition
1) Mesenchymal cells differentiate into osteoprogenitor/osteoblasts cells when they aggregate at ossification center
2) Synth to woven bone by depositing osteoid w/out any cartilage precursor
This is why it generates into woven bone instead of become cart first
3) Additional osteoid deposition occurs on these first bony spiclules and mineralizes etc
4) Eventually, remaining mesenchymal cells give rise to periosteum and endosteum |
|
|
Term
| ENDOCHONDRAL OSSIFICATION |
|
Definition
*Osteoid is laid down on edge\s of calcified cart matrix by osteoblasts derived from osteoprogenitor cells
*Initially woven bone but subsequent remodeling leads to lamellar bone
*Initially may be remnants of cart left but additional remodeling removes all traces of cartilage
*Onec mature (lamellar) bone is formed. i t is histologically indistinguishable from bone tissue formed by intramembranous ossification |
|
|
Term
| Which cytoplasmic structures/organelles would stain particularly well with eosin in FFPE sections, and why? |
|
Definition
cytoskeleton; mitochondria; zymogen granules and similar protein containing vesicles; lysosomes; microvilli; cilia
all of these are either primarily protein, or contain extensive protein as well as other components, and eosin has high avidity for proteins in FFPE specimens |
|
|
Term
| In a cell that secretes lots of protein you will see (TEM): |
|
Definition
Golgi- prominent
RER- extensive
Nucleus- lots of euchromatin, probably doing lots of transcribing and lrg nucleolus
Secretory granules- storing proteins |
|
|
