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Table 3 Notes on fixatives

From: MicroCT for comparative morphology: simple staining methods allow high-contrast 3D imaging of diverse non-mineralized animal tissues

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.
  The most common, but rarely the best fixative. [23, 24]
paraformaldehyde Polymerized formaldehyde, usually dissolved in buffer (e.g. PBS) at 4% w/v when a chemically-controlled fixative is required.
  Action is generally similar to 10% NBF. [23, 24]
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.
  1. In general, the best fixative for microCT scanning will be the best histological fixative for the particular tissues under investigation.