How is histology done on dogs? - briefly
Histology on dogs involves collecting tissue samples through biopsy or post-mortem examination. These samples are then processed by fixing, embedding, sectioning, and staining before microscopic analysis to study cellular structures and disease states.
How is histology done on dogs? - in detail
Histology in dogs involves a systematic approach to examining tissue samples microscopically, which can provide valuable insights into the health and disease states of various organs and systems within the body. The process typically begins with the collection of a representative tissue sample from the dog. This is often done during surgical procedures or post-mortem examinations, ensuring that the tissue remains intact and undamaged to preserve its structural integrity.
The collected tissue sample is then prepared for histological analysis through a series of steps known as histological processing. The first step involves fixing the tissue, which prevents decomposition and preserves the cellular structure. Common fixatives include formalin and glutaraldehyde. Fixation is usually carried out by immersing the tissue sample in the chosen fixative solution for a specified period, typically 24 to 48 hours, depending on the size and type of tissue.
Following fixation, the tissue undergoes dehydration, where water is gradually removed from the cells. This is achieved by exposing the tissue to increasing concentrations of alcohol or other organic solvents. The process starts with a low concentration of alcohol and progressively moves to higher concentrations, ensuring that the tissue is not damaged during this transition.
After dehydration, the tissue sample is infiltrated with a paraffin wax. This step replaces the alcohol with wax, which acts as an embedding medium. Infiltration ensures that the tissue is fully impregnated with wax, preventing the formation of air bubbles and maintaining the structural integrity of the tissue during the subsequent embedding process.
Embedding involves placing the infiltrated tissue into a block of solidified paraffin wax. This step secures the tissue in place, making it easier to handle and slice during the sectioning process. The embedded tissue block is then mounted onto a microtome, a specialized instrument designed for cutting thin sections of tissue.
Sectioning involves carefully slicing the embedded tissue into extremely thin sections, typically ranging from 3 to 7 microns in thickness. These thin sections allow light to pass through them, making it possible to view the tissue under a microscope. The sectioned tissue is then transferred onto glass slides and allowed to dry.
The dried tissue sections are subsequently stained to enhance their visibility under a microscope. Commonly used stains include hematoxylin and eosin (H&E), which differentiate cellular components by coloring nuclei blue and cytoplasm pink, respectively. Other specialized stains may be employed depending on the specific tissue type or disease state being investigated.
Finally, the stained tissue sections are examined under a microscope by a trained histologist or pathologist. They analyze the tissue architecture, cellular morphology, and any abnormalities that might indicate disease processes. The findings from this examination can provide crucial information for diagnosing diseases, monitoring treatment responses, and understanding the underlying mechanisms of various health conditions in dogs.
In summary, histological analysis in dogs involves a meticulous process that includes tissue collection, fixation, dehydration, infiltration, embedding, sectioning, staining, and microscopic examination. Each step is critical for preserving the integrity of the tissue sample and ensuring accurate and reliable results.