2. Introduction To Microanatomy Flashcards
- Describe the basic preparation of tissues for microscopic study (objective)
Answer later
- Describe and recognize common histologic stains and what they are used for (objective)
Answer later
- Describe the relationship between cells and tissues (objective)
Answer later
Epithelial Tissue
Covers exposed surfaces
Lines internal passageways and chambers
Produces glandular secretions
Connective Tissue
Fills internal spaces
Provides structural support
Stores energy
Muscle Tissue
Contracts to produce active movement
Neural Tissue
Conducts electrical impulses
Carries information
Etiology (cause)
Genetic and/or acquired stimuli (inherited mutations, gene variants, infectious agents, chemical insults, physical trauma)
Pathogenesis
Sequence of biochemical and morphologic events arising from cell/tissue response to etiologic agent
(Where treatment happens)
Morphologic Changes
Structural alterations in cells/tissue that are characteristic or diagnostic of an etiologic process
Functional Derangements and Clinical Manifestations
Functional abnormalities resulting from genetic, biochemical, structural changes in cells/tissues (and therefore organs), that give rise to signs and symptoms
Microscopy
Light Microscopy (magnify 2000x, see cells but cannot see smaller stuff) Electron Microscopy (magnify 400,000x, see ribosomes, membranes...)
Ways To Obtain Tissue (list)
FNA
Needle (core) Biopsy
Excisional Biopsy (all of mass)
Autopsy
Tissue Preparation: Fixation
Purpose: to preserve tissue structure and prevent tissue degradation (small pieces placed in chemical solutions; large organs fixed via infusion of chemical solutions into blood vessels)
Most common fixative: Formalin-light microscopy; Glutaraldehyde-electron microscopy
Tissue Preparation: Embedding and Sectioning
Purpose: allow tissue to be sliced thinly enough to be examined by microscope
- Fixed tissue infiltrated with material that imparts a firm texture (Paraffin-light microscopy; Plastic resins-electron microscopy)
- Infiltrated tissue then embedded into a block of material
- Block is sliced very thinly (3-10 micrometers for LM, <1 micrometer for EM) so light can shine through
- Tissue sections placed on glass slides for exam
Tissue Preparation: Staining
Purpose: allow cells and extracellular material to be seen
- Stained with dyes or combinations of dyes to highlight parts
- Hematoxylin and eosin (H&E)
Special Stains
- Stains to highlight different parts of cell or ECM
- Gram stain (determine whether/which type of bacteria are present)
- Wright Giemsa stain (facilitates differentiation of blood cells)
- Immunohistochemistry (allows detection of molecular markers and evaluation of protein expression)
H&E Stain
Stain of choice
Hematoxylin is dark blue or violet that is basic/positive; binds to basophilic substances (acidic or negatively charged like DNA and RNA)
Eosin is red or pink counterstain that is acidic/negative; binds to acidophillic substances (positively charged like cytoplasmic proteins), applied to clarify or distinguish additional features of tissue
H&E: Basic Cell Anatomy (know terms)
Cell, ECM, Nucleolus, Nucleus, Cytoplasm
H&E: Basic Tissue Anatomy
Parenchyma: functional tissue (made of epithelial, absorptive)
Stroma: supporting tissue (connective tissue, blood vessels, nerves…provide mechanical and nutritional support)
Gram Stain
Diagnostic tool in microbiology and infectious diseases
Categorize bacteria based on thickness of peptidoglycan layer in cell membrane
-Tissue stained with crystal violet dye +Gram’s iodine solution, then decolorized and counterstained with safranin or fuschine
-Gram positive bacteria retain violet stain due to thicker peptidoglycan layer
-Gram negative bacteria lose violet stain due to thinner peptidoglycan layer and take up pink counterstain
Wright Giemsa Stain
- Study blood cell morphology and facilitate diagnosis of blood disease like leukemia or bacterial infections
- Combo of stains including methylene blue, azure B and eosin
- Eosin stains cytoplasm pink
- Methylene blue and azure B stain nucleus and components with blue and purple shades
Immunohistochemistry
Uses labeled antibodies to identify antigens (often for infection and neoplasia)
-Normal/cancer cells and microbes have unique antigens
-Markers used to identify microorganisms, benign vs. malignant, identify cell type to determine primary tumor or metastasis, determine stage and grade of tumor.
Also used to determine treatment and response to treatment
Silver stain, always makes brown stains
