Types of tissue specimens I. Cytological - smear, scrape, brushing, washing or fine needle aspirate II. Biopsy (Bx

... Anatomical Pathology - Lecture 1 * Pathology: a study of disease * Types of tissue specimens I. Cytological - smear, scrape, brushing, washing or fine needle aspirate II. Biopsy (Bx) - piece of tissue, trephine, punch specimen III. Whole organ - amputation or mastectomy, appendectomy IV. Post mortem samples, routine or forensic * Tissue preparation modes i. Routine paraffin blocks ii. Urgent surgical cases - frozen sections iii. Enzyme or lipid studies iv. Immunohitochemistry (antibody) v. Special tissue studies (kidney, bone, brain) vi. Electron microscopy vii. Cytology viii. In situ hybridization (DNA or RNA) * Chemical tissue preservation is used to i. Prevents tissue breakdown: autolysis, putrefaction ii. Increases firmness for handling iii. Retains tissue structure iv. Increase permeability for future chemical processing Chemical tissue preservation works: i. Denatures protein, breaking down autolytic enzymes, unfolding molecules ii. Disrupting internal bonds (H+ & 2S-) increasing permeability & leaving molecules to make new links with fixatives and dyes iii. Precipitating proteins and preventing loss during subsequent chemical processing Important factors of chemical tissue preservation i. pH (hydrogen

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