Epithelia III Flashcards
How do common histological dyes function?
They may bind differentially to acidic or basic proteins/amino acids to produce a range of contrast that can be observed.
Key steps for viewing histology samples.
1) Find the nuclei. That tells you where a cell is, how cells are arranged, and a little about the nature of those cells. They also stain very well, and their relative size can imply the level of magnification in the slide.
2) Compare and Contrast features. Are the cells tightly arranged (epithelia), or are they haphazard (connective tissue)?
3) Remember that blank spots do not mean they are empty, only that the dye did not bind anything in there. Different dyes produce very different results.
What is an epitope?
An epitope is the very specific part of a protein that an antibody recognizes and binds to. Generally 15-20 AA in length.
What are the two names for immunostaining?
Immunohistochemistry
Immunoflorescence
What is the procedure for immunostaining?
The sample is fixed on a slide and permeablized to allow the antibody to access the sample and bind to the epitope. The sample is then soaked in a solution containing the primary antibody and then washed to remove unbound antibodies. The sample is then soaked in a solution containing the secondary antibody with is fluorescent and specific to the tail of the primary antibody, so you have antibody-bound-antibodies.
Why is the secondary antibody used instead of a fluorescent primary antibody?
The secondary antibody need only be from the same species as the primary antibody so it is, specific to the tail region of the primary antibody. Thus, you can use one fluorescent antibody to bind thousands of primary antibodies, which is more cost effective.
How can immunostaining aid in diagnosis of cancers and personalized treatment?
The antibodies can be very specific for individual gene products (such as TTF, or Thyroid Transcription Factor) which can then be used to determine exactly what genes are expressed within the cancer cells and help direct treatment.
How is in-situ hybridization used to diagnose cancer?
Complimentary, fluorescent DNA or RNA probes can be used to hybridize with the DNA or RNA transcripts expressed in the cells, showing their relative expression levels. The probes can be manufactured more readily than antibody probes.
