Histological Techniques in Oral Tissue

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the primary purpose of fixing a specimen in tissue preparation?

To preserve the cells in a life-like state (correct)

To enhance the visibility of the tissue under an electron microscope

To ensure the specimen is transparent enough for light microscopy

To make the specimen easier to stain

Which characteristic must a specimen possess for successful examination using light microscopy?

It must be opaque to reduce light scattering

It must be thin and flat with a single layer of cells (correct)

It must be preserved with a high concentration of alcohol

It must be covered with a thick layer of dye

What is the first step in the paraffin embedded section preparation technique for soft tissues?

Mounting the cut sections

Processing of the tissue

Embedding the tissue

Fixation of the specimen (correct)

What type of microscopy would typically be used for examining thick tissues?

Electron microscopy Signup and view all the answers

What role does staining play in the preparation of specimens for light microscopy?

It allows different components of the tissue to be distinguished Signup and view all the answers

Which of the following techniques is NOT used for examining soft tissues?

Ground sections Signup and view all the answers

What is the main characteristic of a decalcified section preparation technique?

It is specifically for hard tissues that have been treated to remove calcium Signup and view all the answers

Under a light microscope, the process that allows tissues to be adequately observed involves which of the following?

Transmitting a beam of light through the thin section Signup and view all the answers

What happens to enamel during the decalcification process?

It is completely destroyed if fully formed. Signup and view all the answers

What is the primary purpose of grinding calci fied tissue specimens?

To obtain thin sections for microscopic examination. Signup and view all the answers

Which method is used for examining soft tissue specimens immediately?

Frozen section technique. Signup and view all the answers

What is the purpose of the microtome in sectioning specimens?

To achieve equal increments of tissue thickness Signup and view all the answers

During the decalcification process, which component primarily remains after the inorganic substance is dissolved?

Organic substance. Signup and view all the answers

Which of the following statements about the frozen section technique is NOT correct?

It is suitable for soft tissue specimens only. Signup and view all the answers

What is the first step in staining a section?

Rehydrating the tissue after paraffin removal Signup and view all the answers

Which dye is referred to as a basophilic stain?

Hematoxylin Signup and view all the answers

What color does eosin stain the basic components of the cells?

Pink Signup and view all the answers

Which component is stained by hematoxylin?

DNA and RNA Signup and view all the answers

In histology, what is the term used to describe components that are stained by eosin?

Acidophilic Signup and view all the answers

What is the typical thickness of tissue sections cut with a microtome?

4 to 10 microns Signup and view all the answers

What happens to the sections after they are placed on glass slides before staining?

They are cooled to room temperature Signup and view all the answers

What is the primary purpose of dehydration in tissue processing?

To remove xative and water from the tissue Signup and view all the answers

Which of the following is NOT a commonly used dehydrating agent?

Xylene Signup and view all the answers

What is the role of xylene in the tissue processing procedure?

To clear the tissue by making it transparent Signup and view all the answers

At what temperature is paraf n wax typically melted during the infiltration process?

65°C Signup and view all the answers

What is the main purpose of the embedding process in tissue preparation?

To facilitate the sectioning of the tissue Signup and view all the answers

What characteristic of xylene makes it suitable for use after dehydration?

It is miscible with both alcohol and paraf n Signup and view all the answers

Why is it important for the specimen to be completely infiltrated with paraf n before embedding?

To distinguish overlapping cells from the extracellular matrix Signup and view all the answers

Which of these statements about the dehydration process is true?

The specimen is passed through increasing percentages of alcohol. Signup and view all the answers

What is the primary aim of fixation in tissue processing?

To prevent autolysis and bacterial attack Signup and view all the answers

Which of the following agents is commonly used for light microscopic examination?

10% neutral formalin Signup and view all the answers

What happens if the concentration of formalin used in fixation is lower than 10%?

The tissue will not fix properly Signup and view all the answers

How does formalin stabilize tissue during the fixation process?

By forming bridges with hydrogen in amino acids Signup and view all the answers

What factors can affect the fixation process?

pH, temperature, penetration of fixative, and volume of tissue Signup and view all the answers

What is a consequence of using a fixative concentration higher than 10%?

The inner tissue will fix too quickly and become dense Signup and view all the answers

What is considered the ideal condition of tissue following fixation?

The tissue should resemble its living state as closely as possible Signup and view all the answers

In the fixation process, what is the first step after transporting the organ to the laboratory?

Storing the organ in formalin Signup and view all the answers

Study Notes

Introduction to Oral Tissue Morphology

Microscopic examination of tissue sections is crucial for understanding oral tissue morphology.
Knowledge of microscopy types and histological techniques is essential for studying structure and function of oral tissues.

Types of Microscopy

Light microscopes and electron microscopes are primary tools for tissue study.
Light microscopy requires thin, translucent tissue sections mounted on glass slides for examination.

Requirements for Light Microscopy Specimens

Cells must be preserved in a "life-like" state through fixation.
Specimens should be transparent to allow light passage.
Specimens must be thin and flat to ensure a single layer of cells.
Staining is necessary for distinguishing different tissue components.

Specimen Preparation Techniques for Oral Tissue

Four common techniques for preparing tissues for light microscopy:
- Paraffin embedded sections for soft tissues.
- Decalcified sections for hard tissues.
- Ground sections for calcified tissues.
- Frozen sections for soft tissues.

Paraffin Embedded Sections

Most common method used for soft tissues (e.g., gingiva, tongue, salivary glands).
Involves steps:
- Fixation of specimen.
- Tissue processing.
- Embedding in paraffin.
- Sectioning.
- Mounting cut sections.
- Staining.

Fixation of Specimen

Fixation prevents autolysis and bacterial damage, preserves volume and shape, and facilitates clear staining.
Common fixatives: 10% neutral formalin and Bouin’s fluid.
Proper fixation is influenced by pH, temperature, and penetration of the fixative.

Processing of Tissue (Dehydration, Clearing, Infiltration)

Dehydration: Replace fixative with dehydrating agents (e.g., alcohol, acetone) to ensure tissue compatibility with paraffin.
Clearing: Transition from alcohol to xylene to make tissue transparent, as xylene is miscible with both.
Infiltration: Use melted paraffin wax to thoroughly saturate the specimen, allowing for better cell distinction.

Embedding Process

Tissue is surrounded by paraffin wax, which solidifies to provide support during sectioning.

Sectioning of Specimen

Paraffin blocks are sliced with a microtome into thin sections (usually 4-10 microns).
Sections are placed on cooled glass slides and stained with specific dyes.

Mounting and Staining

Sections are mounted on adhesive-coated slides and allowed to dry before staining.
Hematoxylin (blue for acidic components) and eosin (pink for basic components) are common stains used in histology.

Comparison of Hematoxylin and Eosin

Hematoxylin:
- Nature: Base
- Stains acidic components (DNA, RNA) blue (basophilic).
Eosin:
- Nature: Acid
- Stains basic components pink (acidophilic).

Decalcified Sections

Used for examining hard tissues that have been demineralized to preserve structure (e.g., bone, teeth).

Ground Sections

For calcified tissues, specimens may be ground to thin sections while preserving the organic matrix post-burn.

Frozen Sections

Employed to analyze pathological tissue specimens immediately or when embedding reagents would alter tissue characteristics.
Sections are cut using a freezing microtome (cryostat) without embedding.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

Explore the essential techniques for preparing and examining oral tissue sections under a microscope. This quiz covers the fundamentals of microscopy and the importance of understanding oral tissue morphology. Test your knowledge on various types of microscopes and histological methods used in the study of oral tissues.