Fixative | Notes |
---|---|
neutral-buffered formalin (10% NBF) | Formalin = 37% formaldehyde solution (aq.). |
 | Normally used at 10% dilution in phosphate buffer at pH 7.0 |
 | Commercial formalin usually contains about 10% methanol. |
 | |
paraformaldehyde | Polymerized formaldehyde, usually dissolved in buffer (e.g. PBS) at 4% w/v when a chemically-controlled fixative is required. |
 | |
gluteraldehyde | Strong cross-linking fixative, often prepared in cacodylate buffer or a less toxic alternative such as HEPES. Common fixative for electron microscopy. [23, 24] |
4F1G | 4% (or 3.7%) formaldehyde + 1% gluteraldehyde in phosphate buffer. |
 | Takes advantage of the faster penetration of formaldehyde and the superior fixing action of gluteraldehyde. Common fixation for electron microscopy. [25] |
Bouin's fluid | 75 parts (v/v) saturated aqueous picric acid, |
 | 25 parts formalin (37% formaldehyde), |
 | 5 parts glacial acetic acid. |
 | A standard and excellent histological fixative. [24] |
alcoholic Bouin's | Refers to either a mixture of Bouin's fluid and ethanol (1:1), or to the fixative also known as Bouin-Duboscq-Brasil [24]. The two are similar in final composition. |
 | The alcoholic solutions penetrate more readily and are sometimes favored for arthropods. |
glyoxal | A cross-linking dialdehyde (OCHCHO) prepared in acidic buffers and marketed as formalin substitutes: Prefer (Anatech Ltd.; http://www.anatechltdusa.com) and Shandon Glyo-Fixx (Thermo Scientific; http://www.thermo.com). |
 | Much less volatile and toxic than formaldehyde. |
 | Very good tissue preservation; especially good for immunostaining. |
Dent's fixative | 80% methanol, 20% DMSO |
 | Rapid dehydrating fixative. Expect some tissue shrinkage. Often used for immunostaining. |
hot alcohol | Samples are dropped into 70% ethanol at about 60°C. |
 | Mainly used for fixing soft-bodied animals, such as insect larvae and pupae. |