What is Tissue Collection?
Tissue collection is a critical process in the field of
histology, involving the procurement of tissue samples from living organisms to study their microscopic structure. The collected tissues are then processed, sectioned, and stained for examination under a microscope to understand various physiological and pathological conditions.
Diagnose diseases, such as
cancer Understand tissue architecture and cellular composition
Investigate the effects of drugs and treatments
Study developmental biology and organogenesis
Biopsy: This is the most common method, where a small piece of tissue is surgically removed from a living organism. Types of biopsies include needle, excisional, and incisional biopsies.
Surgical Resection: Larger tissue samples are obtained during surgical procedures, often used for studying tumors and other large lesions.
Endoscopic Collection: Tissues from internal organs can be collected using an endoscope, a flexible tube with a camera and tools.
Autopsy: Post-mortem tissue collection helps in understanding the cause of death and studying diseases.
Time of Collection: Tissues should be collected as soon as possible after excision to prevent
degradation.
Handling: Gentle handling is crucial to avoid mechanical damage. Use of
sterile instruments is also important to prevent contamination.
Fixation: Immediate fixation in an appropriate fixative, such as
formalin, is necessary to preserve tissue morphology and prevent autolysis.
Labeling: Proper labeling with relevant patient information and tissue site is essential for accurate identification.
What are the Common Fixatives Used?
Fixatives are chemicals used to preserve tissues by stabilizing their structure and composition. The choice of fixative depends on the type of tissue and the intended analysis:
Formalin: The most widely used fixative, ideal for routine histology.
Glutaraldehyde: Used for electron microscopy due to its superior preservation of ultrastructure.
Ethanol: Commonly used for cytological samples.
Bouin's Solution: Useful for preserving delicate structures, such as embryos.
Dehydration: Gradual removal of water using increasing concentrations of alcohol.
Clearing: Replacement of alcohol with a clearing agent, like xylene, to make the tissue transparent.
Embedding: Tissues are embedded in paraffin wax to provide support for sectioning.
Sectioning: Thin slices of tissue are cut using a microtome and placed on slides.
Staining: Tissues are stained with dyes like hematoxylin and eosin to highlight different cellular components.
Degradation: Immediate fixation is required to prevent
autolysis and degradation.
Contamination: Sterile techniques are necessary to avoid microbial contamination.
Ethical Issues: Obtaining informed consent and adhering to ethical guidelines are crucial, particularly in human tissue collection.
Variability: Biological variability and differences in tissue handling can affect the consistency of results.
Conclusion
Tissue collection is a foundational aspect of histology that requires meticulous planning, careful handling, and adherence to best practices to ensure the integrity of samples. It plays a vital role in advancing medical science, from diagnosing diseases to understanding complex biological processes.
