The periodic acid Schiff reaction (PAS reaction) refers to the formation of polyaldehydes after sugar is oxidized by periodic acid, a strong oxidant. The latter is then combined with the colorless magenta sulfuric acid complex (Schiff's reagent) to form a purple-red reaction product. The PAS reaction shows the sugar chains of glycans and glycoproteins, that is, polysaccharides.

Immunohistochemistry is a technique for detecting peptides and proteins in tissues based on the principle of specific binding of antigens and antibodies.

The principle of in situ hybridization is to use a nucleic acid probe with a marker and a known base sequence to perform specific in situ binding, that is, hybridization, with the ribonucleic acid to be detected in the cell according to the principle of base pairing. Display and detection of markers to know the presence and relative amount of the nucleic acid to be tested.

Collodion embedding: making larger tissue blocks (such as eyeballs, brains)

Frozen sections: preserve enzyme activity and lipids

Smears: blood, body fluids, cultured cells, etc.

Spreading: loose connective tissue, mesentery, etc.

Grinding discs: hard tissues such as bones and teeth

Basic dyes (positively charged in solution): hematoxylin, toluidine blue, basic fuchsin, etc.

Acid dyes (negatively charged in solution): eosin, orange G, brilliant green, etc.

In the silver staining method, some organizational structures can directly reduce silver nitrate to display, which is called argyrophilicity. Some structures have no direct reduction effect and require the addition of reducing agents to develop color, which is called argyrophilicity.

A specially labeled nucleotide strand with a known base sequence is used as a probe to hybridize with the DNA or mRNA fragment to be tested.

electron microscopy

Optical microscope: 0.2um, section thickness 1-10um

epithelium

muscle

nerve

connective

A. Histological research includes cells, tissues, organs and systems

B. Cells are the basic units of human body structure and function.

C. A group of cells formed by many cells with similar shapes and related functions and extracellular matrix is ​​called a tissue.

D. Organs are formed by the developmental differentiation and organic combination of several different tissues in the early stages of embryonic development, and perform specific physiological functions at a higher level than tissues in the body.

E. Many organs with similar structures and related functions unite to form a system

F. Extracellular matrix is ​​produced by cells and participates in forming the microenvironment for cell survival.

Darker on a fluorescent screen

It is difficult for electron beams to pass through

The image is darker in the photo

Molecular weight is not necessarily larger

Not necessarily difficult to combine with dyes

The most commonly used staining methods in histology are hematoxylin and eosin staining, referred to as HE staining.

Hematoxylin stains acidic substances such as ribosomes and rough endoplasmic reticulum in the nucleus and cytoplasm purple-blue, and eosin stains alkaline components in the cytoplasm and extracellular matrix light red. A property that has strong affinity with basic dyes and is easily dyed is called basophilia; a property that has strong affinity with acidic dyes and is easily dyed is called acidophilia; if the affinity with both dyes is not strong, it is called acidophilia. , it is called neutral (neutrophilia).

Certain structural components, such as the cytoplasmic granules of mast cells, when stained with basic dyes such as toluidine blue, do not appear blue, but purple-red. This staining characteristic is called metachromasia.

When stained with silver nitrate, some tissue structures can directly reduce silver ions into silver particles and appear black, which is called argen-taffin. Some tissue structures require the addition of reducing agents to develop color, which is called argyrophilia. (argyrophilia).