Histology Lecture 1 Flashcards
Histology bridges…
Physiology and Gross Anatomy
4 main tissues in the body
Connective, epithelium, muscular, and neural
3 types of microscopes
Light microscope, transmission electron microscope, and scanning electron microscope
Light microscope
A compound microscope that is composed of a specific arrangement of lenses that permit a high magnification and good resolution of the tissues being viewed.
Transmission electron microscope
It uses much thinner sections compared with light microscopy and requires heavy metal precipitation techniques rather than water-soluble stains to stain tissues
High magnification
Stream of electrons pass through thin specimen, is refined, and then hits the screen producing a negative image
Scanning electron microscope
provides a 3D image of the specimenviews the surface of the specimen so electrons do not pass through the specimen
Stains
More common: hematoxylin and eosin, and silver stain (reticular fiber stain)
Less common: Masson’s trichrome, periodic acid-Schiff stain, and Wright’s stain
Hematoxylin and Eosin Stain
Most common (what we will be looking at 95% of the time)
Hematoxylin is a basic dye that stains acidic (basophilic) structures (DNA, RNA, etc.) purple
Eosin is an acidic dye that stains basic (acidophilic) structures from pink to orange
Silver Stain/Reticular Fiber stain
uses silver saltreticular fibers become blacksometimes a counterstain is used
Masson’s Trichrome
3 color sating protocol - connective tissue is blue, nuclei and muscle are dark red/purple, and cytoplasm is red/pink
Periodic Acid-Schiff Stain
basement membrane (collagen fiber), glycogen, and other carbohydrates stain magentanuclei stains blue
Wright’s Stain
Common stain w/ blood: nuclei - bluish purple cytoplasm - light pink/grey RBCs - pink neutrophil granule - clear eosiniphil granules - bright red/orange basophil granules - deep purple/violet platelet granule - red/purple
Open-faced vs Close-faced Nucleus
Open-faced - mitotically active; space needed for DNA to unwind
Close-faced - not mitotically active; opaque
Cell Inclusions
nonliving components of cells that do not possess metabolic activity and are not bounded by membranes
what a cell does not directly need to live
most common: glycogen, lipid droplets, crystals and pigments
Glycogen
a type of cellular inclusion
common form of glucose in animals and is especially abundant in cells of the muscle and the liver
important energy source for those cells
Lipid
Triglycerides in storage form is a typical type of cellular inclusion especially as adipocytes but also other cell types including hepatocytes
source of energy and short carbon chains by cell in membrane and hormone synthesis
along with pigments = most common inclusion body seen under H&E Staining
Crystals
Type of cellular inclusion
believed to be crystalline forms of certain proteins common in sertolli and Leydig cells of testes
crystal inclusions found in large cells with sarcoidosis and consisting mainly of calcium oxalate as well as soon calcium carbonatecells do not “like” crystals bc they grow on top of eachother
Pigments
various compounds found in the cell that can serve a protective function (melanin), marks cells age or exposure to oxidative stress (lipofuscin)
along w/ lipid droplets = most commonly seen cellular inclusion with H&E Staining
What are the 2 cellular inclusions seen most commonly with H&E Staining
Lipid droplets and pigments
Melanin
Most common biological pigment
produced by melanocytes (derived from neural crest)
migrate during development to specific places (esp the integument but also some parts of the nervous system)
Hemosiderin
residue of RBC destruction (phagocytized)
Lipofuscin
yellow-brown granules containing residues of lysosomal digestion
considered sign of aging or “wear and tear” pigmentfound in liver, kidney, hear muscle, adrenals and nerve cells
