| Thoma's fixative | Nitric acid in 95% alcohol, used for decalcifying bone in the preparation of histologic specimens. (05 Mar 2000) |
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| Thoma | Richard, German histologist, 1847-1923. See: Thoma's ampulla, Thoma's fixative, Thoma's laws. (05 Mar 2000) |
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| Thoma's ampulla | A dilation of the arterial capillary beyond the sheathed artery of the spleen. (05 Mar 2000) |
| Thoma's laws | The development of blood vessels is governed by dynamic forces acting on their walls as follows: an increase in velocity of blood flow causes dilation of the lumen; an increase in lateral pressure on the vessel wall causes it to thicken; an increase in end-pressure causes the formation of new capillaries. (05 Mar 2000) |
| acetone fixative | Acetone used at low temperatures to fix enzymes, particularly phosphatases; it removes fat and glycogen. (05 Mar 2000) |
| Altmann's fixative | A bichromate-osmic acid fixative. (05 Mar 2000) |
| Bouin's fixative | A solution of glacial acetic acid, formalin, and picric acid, useful for soft and delicate tissues (as those of embryos) and small pieces of tissues; it preserves glycogen and nuclei and permits brilliant staining, but penetrates slowly, distorts kidney tissue and mitochondria, and does not permit Feulgen stain for DNA. (05 Mar 2000) |
| Carnoy's fixative | Ethanol, chloroform, and acetic acid (6:3:1) or ethanol and acetic acid (3:1), an extremely rapid fixative used for glycogen preservation and as a nuclear fixative. (05 Mar 2000) |
| Marchi's fixative | A mixture of Muller's fixative with osmium tetroxide, with potassium chlorate substituted for the potassium dichromate of Muller's fixative for better results; used to demonstrate degenerating myelin. See: Marchi's stain. (05 Mar 2000) |
| Park-Williams fixative | A fixative for spirochetes, comprised of a 2% solution of osmic acid to the fumes of which the bacteria are exposed for a few seconds. (05 Mar 2000) |
| Regaud's fixative | A fixative containing formaldehyde and sodium dichromate, used to preserve mitochondria but not fat; requires afterchroming and extensive washing. (05 Mar 2000) |
| glutaraldehyde fixative | A fixative used in phosphate or cacodylate buffer for electron microscopy, and as a chromatin and enzyme fixative; may be used preceding osmic acid as a second fixative to add membrane preservation for electron microscopy. (05 Mar 2000) |
| Golgi's osmiobichromate fixative | <chemical> An osmic-bichromate mixture used to demonstrate nerve cells and their processes. (05 Mar 2000) |
| Champy's fixative | A mixture of potassium bichromate, chromic acid, and osmic acid, considered an excellent cytologic fixative with advantages and disadvantages similar to those of Flemming's fixative; it differs from Flemming's fixative in substituting bichromate for acetic acid. (05 Mar 2000) |
| methanol fixative | A fixative used with dry blood films, and often incorporated into the stain used. (05 Mar 2000) |
| picroformol fixative | A fixative containing formalin and picric acid. (05 Mar 2000) |