How do we study tissues?
Staining: Use of general or more specific dyes, most common H&E (Haemotoxylin and Eosin). Staining based on ACID/BASE properties and therefore binds to different structures. Eg Haemotoxylin basic, binds to acidic structures such as nucleus. Eosin acidic. In CONJUNCTION, they accentuate different parts of the cell.
Specific Staining: Use of antibodies to identify proteins and highlight the areas on the sample. Immunohistochemistry/Immunocytochemistry. Can also make use of other markers. Eg Fluorescent.
Microscopy: Usually Light, sometimes Electron where a higher resolution is required.
4 Basic classifications of TISSUE
Epithelium means 'Upon Nipple'
Epithelia: Function as interfaces between different biological components, mediating activities such as Selective Diffusion, Absorption/Secretion, Protection and Containment.
Epithelium Types:
Multiple cells with cell to cell junctions, all adhered to a basement membrane.
Basement Membrane (of variable thickness) separates epithelia from underlying supportive tissues, no blood vessels within. Therefore epithelia rely on diffusion of O2. Formed of Basal Lamina(thin sheet of fibrils) and Reticular Lamina(less dense, fibrous).
Number of layers: Simple/Stratified(compound) 1 layer or multiple. Multiple layers located in areas of increased abrasion and wear. Eg, skin or oesophagus.
Shape: Cuboidal/Columnar/Squamous. based on appearance in sections taken at right angles to epithelial surface. In stratified, classify by outermost layer of cells.
Specialisation: Cilia/Keratin. additional layers of different tissue type.