ZOO 3000 Lecture Notes - Lecture 1: Basophil, Putrefaction, Chromophore
8 Feb 2018
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5 steps to microtechnique: fix/harden the tissue chemically, embed in compound for stability (ex. Paraffin, agar, etc: section with microtome (cut a thin section, stain to enhance contrast, mount in permanent medium usually after dehydration. A preservative such as petit"s fluid shouldld: neither shrink nor swell tissue, neither dissolve nor distort tissue, kill bacteria and moulds (prevents putrefaction, render autolytic enzymes inactive. A fixative such as bouin"s fluid should: satisfy as many criteria of preservative as possible, modify tissue to retain integrity through 5 steps of microtechnique increased strength and rigidity, leave proteins (tissue) porous to dyes and stains. Two general classes of fixatives: coagulant make proteins insoluble while maintaining structure, non-coagulant chemically associate with tissue elements without affecting hydrophilic groups. Coagulant fixatives make proteins insoluble while maintainigng structure - examples - ethanol, picric acid. Ethanol replaces free water at high concentration, and disrupts protein hydrophobic and hydrogen bonds.
