Histology Techniques and Equipment

Summary

This video explains the detailed process of preparing tissue samples for microscopic examination in a pathology lab. It covers the entire workflow, starting from specimen accessioning and initial examination, to fixation using formalin to preserve tissues. The tissue is then processed in an automated machine that replaces water with molten paraffin wax. The embedding step involves placing the tissue in a mold to solidify, followed by slicing with a microtome to create thin sections. These sections are smoothed on a water bath, placed on glass slides, de-waxed, and stained with dyes for visualization. This process ensures high-quality tissue preparation for detailed microscopic analysis.

Takeaways

• 😀 Tissue specimens, like moles or ruptured appendices, are processed in pathology labs for microscopic examination.
• 😀 The first step in tissue processing is specimen accession, which involves assigning a unique lab number to identify each patient's sample.
• 😀 A gross examination of the tissue is done by the pathologist or scientist to describe and measure the sample before processing.
• 😀 Tissue samples are placed in a cassette during processing, which holds the tissue in place and aids in the embedding process.
• 😀 Fixation is essential to preserve tissue in a lifelike state and prevent degradation; formalin is commonly used for fixation.
• 😀 After fixation, tissues are placed in a tissue processor to replace water with molten paraffin wax, enabling hardening for sectioning.
• 😀 The embedding center uses both hot and cold surfaces to manipulate paraffin wax and place tissue samples into molds.
• 😀 The microtome, similar to a deli slicer, is used to cut tissue samples into thin sections as thin as paper for microscopy.
• 😀 Safety protocols must be followed when using the microtome to ensure safe operation during tissue sectioning.
• 😀 The thin tissue sections are floated on a water bath to smooth out wrinkles before being placed onto a glass slide for staining.
• 😀 Once on the slide, the wax is removed, and tissue sections are stained to visualize tissue structures under a light microscope.

Q & A

What is the first step in tissue processing after a specimen is received?

The first step is specimen accession, where the tissue is assigned a unique lab number, and patient details are confirmed to ensure correct identification.

What is the purpose of fixation in tissue processing?

Fixation preserves the tissue in a lifelike state, preventing tissue degradation and maintaining the structure for microscopic examination.

Which fixative is most commonly used in tissue processing?

Formalin, also known as formaldehyde, is the most commonly used fixative in tissue processing.

How does a tissue processor work?

A tissue processor is an automated machine that removes water from the tissue and replaces it with molten paraffin wax to solidify the tissue for sectioning.

What is the function of the embedding center in tissue processing?

The embedding center holds the paraffin wax at a high temperature to keep it liquid, facilitating the embedding of tissue into a mold.

What equipment is used to cut the tissue into thin sections?

A microtome, similar to a deli slicer, is used to cut the tissue into very thin sections, typically as thin as a piece of paper.

Why is a water bath used in the tissue sectioning process?

A water bath is used to smooth out any wrinkles or creases in the tissue sections, ensuring the tissue is flat before transferring it to a glass slide.

How are the tissue sections transferred to glass slides?

Once the tissue sections are flattened in the water bath, they are carefully picked up and placed onto a glass slide.

What happens after the tissue section is placed on the glass slide?

The paraffin wax that supports the tissue is removed, and the tissue is stained with dyes to highlight its structures for microscopic visualization.

What is the final goal of preparing tissue samples for microscopic examination?

The final goal is to produce a stained glass slide with a thin tissue section, allowing pathologists to analyze the tissue's structure and make diagnoses.