Introduction to Human Biology Practicals

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Questions and Answers

What is the main purpose of a microtome in tissue preparation?

To remove paraffin wax from tissue

To stain the tissue sections

To store the paraffin blocks

To cut tissue into thin sections (correct)

What is the thickness range of sections produced by a microtome?

1-2 µm

10-15 µm

3-10 µm (correct)

20-25 µm

What process is used to eliminate wrinkles from the tissue ribbon?

Covering with a glass slide

Lowering onto a water bath (correct)

Rehydration with alcohol

Staining with Hematoxylin

Which of the following is NOT part of the staining process for tissue sections?

Embedding in paraffin wax Signup and view all the answers

What is the function of xylene in the tissue preparation process?

To clear paraffin wax from the tissue Signup and view all the answers

What color does Hematoxylin stain nuclei in tissue sections?

Blue Signup and view all the answers

Which alcohol percentage is directly used before rehydration with water?

100% Signup and view all the answers

In the preparation of tissue sections, what is the final step after staining?

Dehydration Signup and view all the answers

What is the primary purpose of microtechniques in histology?

To prepare, process, and examine histological tissue samples Signup and view all the answers

Which of the following techniques is described as the fastest?

Freezing Technique Signup and view all the answers

What is the first step in the paraffin technique?

Obtaining fresh tissue Signup and view all the answers

Why is fixation important in tissue processing?

It allows tissues to remain in a life-like state Signup and view all the answers

What thickness are tissue sections typically cut to during the paraffin technique?

3-8 microns Signup and view all the answers

Which characteristic makes the paraffin technique the most common?

It provides excellent detail and preservation Signup and view all the answers

What type of tools are recommended for tissue dissection to minimize damage?

Sterile sharp dissecting tools Signup and view all the answers

In which step of the paraffin technique are tissue samples mounted on glass slides?

Cutting Signup and view all the answers

What is the primary purpose of a fixative in tissue preparation?

Denature proteins to prevent autolysis Signup and view all the answers

During which step is bound water removed from the tissue?

Dehydration Signup and view all the answers

What is the typical concentration progression of alcohol used in the dehydration step?

70%, 85%, 95%, 100% Signup and view all the answers

What is the role of clearing agents in tissue processing?

Replace alcohol with a medium for embedding Signup and view all the answers

At what temperature is melted soft paraffin typically heated for infiltration?

50°C Signup and view all the answers

What is the primary function of embedding in the tissue preparation process?

To create a supportive wax block around the tissue Signup and view all the answers

Why is it important to keep the tissue sample size small during fixation?

To ensure proper fixative penetration Signup and view all the answers

What is the melting point range for hard paraffin used in embedding?

55-60°C Signup and view all the answers

Study Notes

Introduction to Microtechniques

Microtechniques involve preparation, processing, and examination of histological tissue samples at a microscopic level.
Essential for preserving tissue structures and highlighting specific cellular components.

Types of Microtechniques

Paraffin Technique: Most widely used method.
Celloidine Technique: Known for its perfection.
Freezing Technique: Fastest method for tissue preparation.

Paraffin Technique Steps

Tissue Collection: Fresh tissue obtained using sterile blunt-cutting tools to minimize damage, followed by preservation in fixatives.
Fixation: Chemical preservation to prevent tissue autolysis, enhance dye attachment, and improve optical differentiation. Common fixative is 10% buffered formalin.
Dehydration: Gradual removal of water using progressively higher concentrations of ethanol.
Clearing: Replacement of alcohol with a clearing agent like xylene.
Infiltration/Impregnation: Removal of clearing agent and permeation of tissue with melted paraffin wax heated slightly above melting point.
Embedding: Placement of infiltrated tissue in a mold filled with hard paraffin to create solid wax blocks for easier sectioning.

Tissue Sectioning and Staining

Microtomy: Technique for cutting tissue into extremely thin sections (3-10 µm) using a microtome. Sections laid on a water bath to eliminate wrinkles.
Staining: Reverses the paraffin removal process for dye penetration:
- Use clearing agent followed by rehydration through descending alcohol grades.
- Common stains: Hematoxylin (stains nuclei blue) and Eosin (stains cytoplasm pink).

Preparation Notes

Emphasize the importance of sample size and fixative volume for optimal preservation.
Record keeping: Embed tissue with clear labeling on cassette including tissue name, fixative type, and date.
Ensure proper drying time for slides before staining to maintain integrity of tissue sections.

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Description

This quiz focuses on the practical aspects of the Introduction to Human Biology (IHB102) course at Dubai Medical College for Girls. It covers essential microtechniques used in biological preparation and examination. Prepare to test your understanding and application of these concepts in human biology.