Histotechnology questions & answers rated A+ 2023/2024

fixitive used for specimens - correct answers 10% neutral buffered Formalin Marking Margins - correct answers - to identify resection margins, if tumour too close to these margins they know they have to go in and cut more out - Guide to embedding What is used to clean grossing station - correct answers phenolic disenfectant or gluteroldehyde how long is specimens stored for - correct answers 1-3 months some legal cases kept indefinitly Why is fresh tissue not stored? - correct answers Would decompose What temperature is an ultra cold freezer kept at - correct answers -70 degrees If specimen Is a known hepatitis, what special precautions are taken - correct answers fixed for 24hrs rather than 4hr If specimen is known CJD, what special precautions are taken? - correct answers resist inactivation with 20% formalin or 70% alcohol fixed for minimum 1 week in phenolized formaline, dissenfect with sodium hydroxide What should be used to label - correct answers Pencil Effects of fixation - correct answers - solidification of colloid materials - Hardening of tissue ( fortify and stabalize) - optical differentiation - preserves cells and tissue in a life-like form - stainability Criteria of a good fixative - correct answers not shrink or distort tissue kill bacteria and fungi render autolytic process inactive Causes of improper fixation - correct answers delay, inadequate amount, poor penetration, use of fixative not suitable for the tissue factors effecting process of fixation - correct answers Time denisty of tissue Choice of fixative Temperature Agitation Vacuum Buffers and hydrogen ion concentration Osmolality 10% neutral buffered formalin - correct answers universal disodium hydrogen glycogen trapped no effect on lipids cationic dye enhanced IMH study preserves some antigens and enzymes - Formaldehyde will polymerize into a white precipitate, remove by filtering, methanol will prevent - below Ph 6.0 causes breakdown will react with blood causing pigment called acid foraldehyde hemetin Gluteraldehyde - correct answers CHO(CH2)3CHO glycogen trapped no effect on lipids - primary fixative for electron microscopy - excellent morphology - False positive PAS result good for all tissue and kidney biopsy Osmium Textroxide - correct answers - Secondary fixative for electron microscopy - turns lipids black - must be buffered at 4 degrees Ethanol - correct answers - Best for glycogen dissolves lipids best for cell fixation used for cytology specimens and glycogen studies - causes severe shinkage, starts dehydration process B5 - correct answers - compound no reaction on glycogen or lipids - enhances cytoplasm nuclei - has mordant properties good for small tissues and HC antigens - Mercury inhibits freezing - used as secondary fixative - leaves uniform black pigment, removed with alcoholic iodine and sodium thiosulfate Zinc formalin - correct answers can be used instead of B5 Glycogen is trapped, no reaction on lipids - Good IHC - enhances nuclear detail, good morphology