Tissues in histopathology are carried out in?

RUHS, Jaipur, M.Sc Nursing Entrance Exam-2018

Pathology & Genetics

Easy

Appeared in: RUHS, Jaipur, M.Sc Nursing Entrance Exam-2018

Explanation

10% buffered formalin is the most widely used and standard fixative for routine histopathological examination.
It works by cross-linking proteins within the tissue, which arrests cellular processes, prevents autolysis (self-digestion), and hardens the tissue.
This preservation of morphology is crucial for accurate diagnosis using standard staining techniques like Hematoxylin and Eosin (H&E).
Its properties provide a good balance between preserving structure and allowing for a wide range of subsequent staining procedures.

Option B: Normal saline is an isotonic solution, not a fixative. It does not stop tissue decay and is only suitable for keeping tissue moist for a very short duration, such as transport to the lab for a frozen section.
Option C: 2% glutaraldehyde is a much stronger cross-linking agent than formalin. While it provides excellent preservation, it is primarily used for electron microscopy (EM) to visualize subcellular structures (ultrastructure), not for routine light microscopy.
Option D: Carnoy's fixative is a special-purpose, non-aqueous fixative. It is not used for routine histopathology because it causes significant tissue shrinkage and distortion.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Specimen Fixation for Histopathology as background academic context rather than a clinical decision trigger.
A nurse's primary responsibility is to ensure the specimen is placed in the correct preservative immediately after collection. Using the wrong fluid (e.g., saline instead of formalin) can render a biopsy diagnostically useless, potentially delaying a cancer diagnosis.
The nurse must ensure the fixative volume is adequate (10-20 times the specimen volume) for proper fixation. An inadequately fixed specimen may have a well-preserved outer layer but a decayed, unreadable core.
What if? If a surgeon requests a 'frozen section' on a specimen, the nurse must NOT place it in formalin. It should be sent to the lab immediately, fresh, or on a saline-moistened gauze, as the freezing process itself is used for preservation before sectioning.

How to Approach the Question

First, identify the core of the question: it asks for the standard medium used in 'histopathology'.
Recognize that 'histopathology' involves examining tissue structure, which requires preservation (fixation) to prevent decay.
Recall or deduce the function of each option. 'Saline' is for hydration, not preservation. This eliminates one option.
Differentiate between the remaining fixatives. 'Formalin' is the most common and standard fixative in pathology labs.
Associate specialized fixatives like 'glutaraldehyde' with specific, non-routine techniques like electron microscopy, and 'Carnoy's' with special stains.
Conclude that for general, routine histopathology, 10% buffered formalin is the correct answer.

Concept Tested & Keywords

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E6 PATHOLOGY QUICK REVIEWBased on Harsh Mohan Textbook of PATHOLOGY p. 77-79