L1 Intro and LM

Question 1

LO2: val of histol in diag.

Answer 1

• often not treat til histopathologists give diag eg CA and ulcerative colitis aka crohns. conf uncl diag. lung CA disting small cell chemo or non small cell surgery. breast CA after feel/mammog/US, stain for oestrogen and progesterone Rs and for prot from HER2 oncog informs tx. melanoma.

Question 2

LO3: units

Answer 2

mm 10-3m, um 10-6m, nm 10-9m, A 10-10m. most hum cells 10-20um. oocyte 100um, can see. RBC 7.2um.

Question 3

LO4: desc comm biop techs eg curretage, needle, transvasc. which tiss sampled by each meth.

Answer 3

biop=rem small piece tiss from organ or part of bod for microsc exam.

• smear cervix or buccal cav, us squam epith.
• curettage scoop endometrial lining uterus.
• needle- brain, breat, liver, kidney, musc.
• dir incis skin, mouth, larynx.
• endoscop lung, int, bladd. flexib tube with cam.
• transvasc heart, liver. in maj vess, foll probe with x ray.

Question 4

LO5: why tiss reqs fixing and comm fixatives. how proc can cause shrinkage artefs.

Answer 4

• fresh biop wet and bloody. glutarald and formald fix. macromolec x linked, cell struc preserved, no autolysis or putrefaction from lysos enzs, and prev bact. ethanol dehyd>xylene/toluene clearing, 56y deg embedd in wax or plastic. 15um sectioning microtome, water sol stain req rehyd by xylene ethanol water>staining>dehyd water ethanol xylene>mounting by sett with organ solvent eg DPX.

Question 5

LO6: compons stained by periodic acid schiff reac and haematoxylin and eosin.

Answer 5

• H stains acidic compons purp eg nucleolus rna, chromatin dna. E stains basic compons pink eg cytop prots, extracell fibs.
• PAS stains carbs and glycoprots magenta. eg mucus sec glands and goblet cells GIT. stains BMs.
• weigerts elastin stains elastic fibs black.
• elastic van gieson stains coll pink, elastin blue, musc yell.

Question 6

LO7: advs of phase contr, dark field, fluor, confoc LM.

Answer 6

• phase contr- unst cell alts light so waves in phase become out of phase. =better contrast than BF. allow live cell, and helps to disting and see int contents eg organelles. in phase=bright, out of phase dim.
• differential interf contr microsc also explout interf when two sets waves comb. incr detail live cell.
• dark field- light shone sideways across cell and is scatt. show perinuc organelles and microbes eg malaria and syphillis inducing.
• fluor- mAb specif stains. eg tubulin mt lab Ab coup to fluorescein. actin Ab coup to rhodamine show mito to spindle, metaph chroms lab dye that fluoresces when bound dna. See cell loc indiv struc/subst. Stains autofluor (abs incid short w/l= illumine and instant re emit longer w/l), or conjug to subst with that prop eg fluorochrome. UV often used as incid rad can= diff col dep on fluorochrome. Filters stop high int UV reaching image plane.
• confoc- tiss lab with >1 fluor probe us. in LM fluor outs reg of int decr resol. confoc elims out of foc flare. scann 1+ laser x specim, excites flurochromes. optic sections. living samps. elec 3d ims.

Question 7

LO1: meaning of tissue.

Answer 7

collec of cells spec to perf partic func. eg epith, connec, musc, nervous. STRUC REL TO FUNC.