Introduction to Cell Histology Flashcards
What are the 4 categories of tissue found in the human body?
Epithelium- protection
connective
Muscle tissue
Nervous tissue
How do histoligists prepare tissues?
Fixation- inactivate degrading enzymes, preserve tissue (typically formalin
Dehydration- remove water using alcohol solutions
Clearing- remove alcohol solution using organic solvent (tissue becomes more translucent)
Infiltration- by placing tissue in wax or plastics
Embedding- harden tissue
Trimming and sectioning- very thin slices
Staining- this
What are the most common dyes used?
Hematoxylin
Eosin
Hematoxylin
What color and what structures does it dye?
blue dye
Cationic– carries net positive charge
— stains negatively charged molecules (nucleic acids carboxyl group of proteins)
Basic dye- dyes basophillic structures
– DNA, RNA, Ribosomes (rough ER and nucleolus), secretory vessicles/granuoles
What color is Eosin and what does it dye?
Pink
Carries net negative charge (anionic)
– stains positively charged molecules (amino group of proteins)
Acidic dye- dyes acidophillic structures
- ECM (collagen), membranes, cytoplasm, cytoskeleton
What are some characteristics of these in H&E dye?
Nucleus, cytoplasm, rER
Nucleus- largest thing in cell, distinct boundary, Nucleoli and nuclear membrane, BASOPHILLIC
Cytoplams- ACIDOPHILLIC, no distinct boundaries between cells.
rER- BASOPHILLIC, granular appearance in cytoplasm
What can you typically not see in the cell with dyes?
plasma membrane- stains pink but can't tell from cyto sER Golgi apparatus mitochondria lysosomes endosomes
There is a cheat sheet to print out in slides
Why does sER not stain too great?
lipids don’t stain too well and sER manufactures lipids.
May be able to distinguish because there will be a hole where it should have been.
Will we see cytoskeleton in stains?
Yes if there are lots of microtubules, actin… like in muscle
acidophilic– bright pink
what are lipid droplets and how can you see them in the cell?
They are cells synthesizing lots of lipids. you will see white ‘droplets’ in the cell.
What happens to erythrocytes in stain?
Stain bright pink or red,
Seen as either single cell or capillaries will stain
What happens to collagen in stain?
Stains bright pink
extracellular matrix
What shapes are epithelial cells?
Where do you find them?
Cuboidal, squamous or columnar
Any linings- skin, respiratory/urinary, GI
Also form serous membranes- membranes that lines body cavity
Forms glands
Epithelial cell structure
Single nucleated
packed and layered, connected to basement membrane
Polar- have directionality, basal and apical surfaces
Avascular- get nutrients and oxygen through diffusion
—except glands are vascularized
All have capability of regeneration
Describe
Squamous, cuboidal and columnar
stratified vs simple
squamous- flat, wider than they are tall
Cuboidal- same wide and tall (spherical nucleus)
columnar- taller than wide (oval nucleus)
cell shape defined by apical layer
stratified- more layers
simple= one layer
What are the two types of glands?
Exocrine- Duct
Endocrine- ductless
anytime you see capillaries in epithelial tissue it will be endocrine gland.
Abluminal vs adluminal
Abluminal= the surface away from the cavity
Adluminal= surface close to the cavity
– will contain the surface specialization (microvilli, cilia)
What is mesothelium?
sinle layer of cells that exist as protective layer lining closed cavities of the body
- pleura (lungs)
- peritoneum (abdomen)
- –serous pericardium (heart)
What is endothelium?
Single layer of cells that lines the inner walls (lumen) of blood and lymph vessels.
What are some characteristics of connective tissues?
4 listed
- Widely separated cells with ECM between
- Rich blood supply (except cartilage)
- provide support and connection
- Underlies or supports other basic tissues.
What are the three major components of connective tissue?
- cells
- fibers (ECM)- collagen or elastic
- ground substance (ECM)
ECM is secreted by the cells in that matrix.
What are the two types of connective tissue proper?
What are their characteristics?
- Loose- collagen loosely packed, abundant ground substance, cells ‘floating’ in substance
- Dense- abundant collagen fibers, little ground substance, cells packed between collagen fibers.
Fibroblast= primary cell type in connective tissue proper
– responsible for secreting collagen, elastin, and ground substance.
Regular vs irregular dense connective tissue (proper)
Regular- collagen fibers parallel to one another, fibroblasts sandwiched between collagen fiber layers. striped appearance.
Irregular- collagen fibers & fibroblasts halfhazardly arranged
Bone
cell type, fibers, ground substance
cell types: osteocytes (maintain), osteoclasts (absorb matrix), osteoblasts (secrete matrix)
Fibers: collagen
Ground substance: hydroxyapatite crystals (solid)
