2. Introduction To Microanatomy

Question 1

1. Describe the basic preparation of tissues for microscopic study (objective)

Answer 1

Answer later

Question 2

2. Describe and recognize common histologic stains and what they are used for (objective)

Answer 2

Answer later

Question 3

3. Describe the relationship between cells and tissues (objective)

Answer 3

Answer later

Question 4

Epithelial Tissue

Answer 4

Covers exposed surfaces
Lines internal passageways and chambers
Produces glandular secretions

Question 5

Connective Tissue

Answer 5

Fills internal spaces
Provides structural support
Stores energy

Question 6

Muscle Tissue

Answer 6

Contracts to produce active movement

Question 7

Neural Tissue

Answer 7

Conducts electrical impulses

Carries information

Question 8

Etiology (cause)

Answer 8

Genetic and/or acquired stimuli (inherited mutations, gene variants, infectious agents, chemical insults, physical trauma)

Question 9

Pathogenesis

Answer 9

Sequence of biochemical and morphologic events arising from cell/tissue response to etiologic agent

(Where treatment happens)

Question 10

Morphologic Changes

Answer 10

Structural alterations in cells/tissue that are characteristic or diagnostic of an etiologic process

Question 11

Functional Derangements and Clinical Manifestations

Answer 11

Functional abnormalities resulting from genetic, biochemical, structural changes in cells/tissues (and therefore organs), that give rise to signs and symptoms

Question 12

Microscopy

Answer 12

Light Microscopy (magnify 2000x, see cells but cannot see smaller stuff)
Electron Microscopy (magnify 400,000x, see ribosomes, membranes...)

Question 13

Ways To Obtain Tissue (list)

Answer 13

FNA
Needle (core) Biopsy
Excisional Biopsy (all of mass)
Autopsy

Question 14

Tissue Preparation: Fixation

Answer 14

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

Question 15

Tissue Preparation: Embedding and Sectioning

Answer 15

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

Question 16

Tissue Preparation: Staining

Answer 16

Purpose: allow cells and extracellular material to be seen

• Stained with dyes or combinations of dyes to highlight parts
• Hematoxylin and eosin (H&E)

Question 17

Special Stains

Answer 17

• 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)

Question 18

H&E Stain

Answer 18

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

Question 19

H&E: Basic Cell Anatomy (know terms)

Answer 19

Cell, ECM, Nucleolus, Nucleus, Cytoplasm

Question 20

H&E: Basic Tissue Anatomy

Answer 20

Parenchyma: functional tissue (made of epithelial, absorptive)

Stroma: supporting tissue (connective tissue, blood vessels, nerves…provide mechanical and nutritional support)

Question 21

Gram Stain

Answer 21

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

Question 22

Wright Giemsa Stain

Answer 22

• 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

Question 23

Immunohistochemistry

Answer 23

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