Histology Lab Intro pdf Flashcards
The study of the tissues of the body and how these tissues are arranged to constitute organs.
Histology
Involved in all aspects of tissue biology, with the focus on how cells’ structure and arrangement optimize functions specific to each organ.
Histology
Tissue have two interacting components:
__
__
Cells Extracellular Matrix (ECM)
Supports the cells and the fluid that transports nutrients to the cells, and carries away their catabolites and secretory products.
EXTRACELLULAR MATRIX (ECM)
Consists of many kinds of macromolecules, most of which form complex structures, such as collagen fibrils and basement membranes.
EXTRACELLULAR MATRIX (ECM)
What are the complex structures contained in the ECM?
collagen fibrils
basement membranes
The cells produce the ECM and are also influenced and sometimes controlled by __ __
matrix molecules
Cells and matrix interact extensively, with many components of the matrix recognized by and attaching to __ __ __.
cell surface receptors
Many of these __ __ span the cell membranes and connect to structural components inside the cells.
protein receptors
__ __ has been invaluable in studying the functions of molecules
Cell culture
It allows the direct observation of cellular behavior
Cell Culture
In preparing cultures from a tissue or organ, cells must be dispersed __ or __
mechanically
enzymatically
Once isolated, the cells can be cultivated in a __ __ to which they adhere, usually as a __ __ _ __
clear dish
single layer of cells
Why is the ideal microscopic preparation preserved?
so that the tissue on the slide has the same structure and molecular composition as it had in the body
Why are cell and tissue structure treated and preserved immediately after removal from the body?
to avoid tissue digestion by enzymes present within the cells (autolysis) or by bacterias.
Fixation usually involves immersion in solutions of stabilizing or cross-linking compounds called __.
fixatives
What are the 4 kinds of popular fixatives?
Aldehyde
Picrates
Alcohol
Oxidizing Agent
What are the aldehyde fixatives?
Formalin - Formaldehyde
Glutaraldehyde
Paraformaldehyde (PFA)
What are the picrates fixatives?
Bouin’s solution
What are the alcohol fixatives?
Ethanol
Methanol
What are the oxidizing agent fixatives?
osmium tetroxide
potassium dichromate
Potassium permanganate
chromic acid
Tissues are embedded in a __ __ to facilitate __.
solid medium
sectioning
In order to cut very thin sections, tissues must be __after fixation with embedding material that imparts a __ __ to the tissue.
infiltrated
rigid consistency
What are included in the embedding materials?
paraffin
plastic resins
used routinely for light microscopy
paraffin
used for both light and electron microscopy
plastic resins
tissue impregnation
PARAFFIN EMBEDDING
• When tissue is filled with liquid paraffin, the impregnated tissue then hardens in a small container of paraffin at __ __.
room temperature
Paraffin embedding is preceded by two other main steps:
__
__
Dehydration
Clearing
A hardened block containing tissue and paraffin is placed in an instrument called a __ and sliced by the steel blade into extremely thin sections.
microtome
• Paraffin sections are generally cut at __ __ thickness
1-10 μm
The very thin sections are placed on __ __ and __
glass slides
stained
Most cells and extracellular material are __ __, and to be studied microscopically sections must typically be stained (dyed)
completely colorless
Cell components such as nucleic acids with a net negative charge (anionic) stain more readily with __ __ and are termed __; cationic components, such as proteins with many ionized amino groups, have affinity for __ __ and are termed __
basic dyes
basophilic
acid dyes
acidophilic
Examples of Basic dyes
toluidine blue
alcian blue
methylene blue
hematoxylin
Examples of Acid dyes
eosin
orange G
acid fuchsin
What is the most used staining method?
simple combination of hematoxylin and eosin (H&E)
