Lecture 1 - Microanatomy (Histology)and Embryology Flashcards
Anatomy definition
The science which deals with structures of healthy body of animals and humans. The structure is revealed by naked eye observation and it is based on dissection`
Gross Anatomy definition
encompasses all those structures accessible by dissection and direct inspection
Microanatomy - histology definition
study of the tissues of the body and how cells and tissue integrate to form organs.
involves all aspects of tissue biology with emphasis on cell structure and function, including functions specific to each organ
Embryology definition
the science which deals with ontogenetic development i.e. with development of a new individual (development of embryo and fetus).
Three branches of histology
Cytology
General histology
Special histology
Cytology
deals with the structure and function of the cell
General histology
deals with the structure of tissue
Special histology
deals with microscopic structure of organs (also called organology)
Histological slides are cut about how big?
4-8 micrometers
Two interacting components that make up tissues
Cells
Extracellular matrix
Extracellular matrix
Anything next to and between cells
Light microscopy
Light beam is transmitted through a tissue
Light microscopy includes (6)
- Conventional bright field microscopy
- Fluorescence
- Phase-contrast
- Differential interference
- Confocal
- Polarizing
Most common light microscopy
Bright field microscopy
Bright field microscopy
requires staining, suchas cytochemical demonstration of mitochondria in sperm
Two types of microscopes
Phase contrast microscopy
Fluorescence microscopy
Phase contrast microscopy basis
-Based on principle that light changes speed when passing through structures with different refractive indices.
Phase contrast microscopy use
Allows observation of living non-stained structures
Fluorescence microscopy basis
Based on affinity of fluorescent compounds for specific cell components
Advantages of LM (4)
- Relatively inexpensive
- Provides rapid diagnosis
- Allows observation of living specimens
- Resolving power of LM id 0.2 micrometers
Disadvantages of LM (4)
- 2-D image
- Resolving power is limited by the wavelength of light
- Requires maintenance
- Requires expertise for proper diagnosis (quality analysis and quality control)
Stereomicroscope
- Also called dissecting microscope
- Uses whole mount
Advantages of dissecting scopes (4)
- Relatively inexpensive
- Practical/versatile
- Can provide 3D image
- Can be used in microsurgery and with other types of specimens
Disadvantages of dissecting scopes (2)
- Low resolving power
- Needs to be maintained
Transmission Electron Microscopy
Very thin slides
Can go inside cells
Scanning electron microscopy
Just scans the surfaces
Useful for structures that live on surfaces such as parasites
Transmission electron microscopy is based on
the interaction of electrons and tissue components
What causes the 1,000 fold increase in resolution with TEM?
The wavelength in the electron beam is shorter
Advantages of TEM (2)
- Great resolving power (0.16-0.18 nanometers)
- Very useful for rapid diagnosis of viruses and other microscopic organisms
Disadvantages of TEM (4)
- 2D
- Black and white
- Can’t be used in living object
- Very expensive
3 conditions objects must meet to be observed under LM or TEM
- Must be fresh and well-preserved in order to retain structure and molecular composition
- Must be thin enough to allow light transmission
- Must have enough contrast to observe details
7 steps for tissue processing for observation in a microscope
- Take it out
- Fixation (12-24 hours)
- Dehydrate using alcohol
- Clearing
- Embed in paraffin wax
- Cut using microtome
- Stain to create contrast
What do we use for fixation?
10% buffered formalin to penetrate tissue
What do we use for clearing?
Xylene
How thick do we cut slides?
1-7 micrometers
What is the most common stain used in routine staining?
Hematoxylin – eosin
Example of special staining?
silver stain use to demonstrate elastin.
What are histochemical methods of staining used for?
used to demonstrate chemical constituients DNA, RNA, lipids, glycogen, carbohydrates and elements such as Ca, Fe etc.
