Chapter 7

Question 1

_____ does not provide adequate fixation in some cells and tissues, like connective tissues, mucus, and bone marrow.

Answer 1

Neutral buffered formalin

Question 2

There are two major groups of chemical fixatives:

Answer 2

Crosslinking Fixatives
Precipitating (or denaturing) fixatives

Question 3

act by creating covalent chemical bonds between proteins in tissue. This anchors soluble proteins to the cytoskeleton, and lends additional rigidity to the tissue.

Answer 3

crosslinking fixatives

Question 4

act by reducing the solubility of protein molecules and (often) by disrupting the hydrophobic interactions that give many proteins their tertiary structure. The precipitation and aggregation of proteins is a very different process from the crosslinking that occurs with the aldehyde fixatives.

Answer 4

Precipitating (or denaturing) fixatives

Question 5

example of crosslinking fixatives

Answer 5

aldehydes

Question 6

example of Precipitating (or denaturing) fixatives

Answer 6

alcoholic fixatives

Question 7

the most commonly used fixative in histology is ______

Answer 7

formaldehyde

Question 8

which fixes the tissues by forming cross-linkages in the proteins, particularly between lysine residues

Answer 8

formaldehyde

Question 9

The standard solution is ___ neutral buffered formalin or approximately ______ formaldehyde in phosphate- buffered saline

Answer 9

10% NBF
3.7-4.0% formaldehyde in PBS

Question 10

_____ prevents acidity that would promote autolysis and cause precipitation of formol-heme pigment in the tissues.

Answer 10

buffer

Question 11

other benefits of ______ include long term storage and good tissue penetration. It is particularly good for immunohistochemistry techniques, and _______ vapor can be used as a fixative for cell smears.

Answer 11

formaldehyde

Question 12

______ is a gas produced by the oxidation of methyl alcohol, and is soluble in water to the extent of 37-40% weight in volume.

Answer 12

formaldehyde

Question 13

The commercially available solution of formaldehyde contains _____ gas by weight (equivalent to 40% stock or concentrated formalin).

Answer 13

35-40%

Question 14

The most widely used fixative for routine histology is _____ buffered to pH __ with phosphate buffer.

Answer 14

10% neutral buffered formalin
pH 7

Question 15

It is considered the fixative of choice for many other procedures that require paraffin embedding, including immunohistochemistry and interphase Fluorescent In-Situ Hybridization (FISH).

Answer 15

buffered formalin