| Rf | in paper or thin-layer chromatography, the distance that a spot of a substance has moved from the po... |
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| YS | yellow spot; yolk sac |
| ys | yellow spot; yolk sac |
pin-head pigmentation spot
| blue spot | A bluish stain on the skin caused by the bites of fleas or lice, especially pediculosis pubis. Synonym: blue spot, tache bleuatre. (05 Mar 2000) |
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| cafe-au-lait spot | <dermatology> A pigmented cutaneous lesion, that can range from light to dark brown, and is due to an excess of melanosomes in the malpighian cells, rather than to an excess of melanocytes. Caf |
| Mariotte's blind spot | The portion of the optic nerve seen in the fundus with the ophthalmoscope. It is formed by the meeting of all the retinal ganglion cell axons as they enter the optic nerve. Because the retina at the optic disk has no photoreceptors there is a corresponding blind spot in the visual field. (12 Dec 1998) |
| cherry-red spot | The ophthalmoscopic appearance of the normal choroid beneath the fovea centralis, appearing as a red spot surrounded by white retinal oedema in central artery closure or lipid infiltration in sphingolipidosis. Synonym: Tay's cherry-red spot. (05 Mar 2000) |
| cherry-red spot myoclonus syndrome | <syndrome> A neuronal storage disorder in children characterised by a cherry red spot at the macula, progressive myoclonus, and easily controlled seizures; the result of sialidase deficiency. Type 1 is characterised by normal body habitus, cherry red macula, myoclonus, and normal beta-galactosidase levels; type 2 by short stature, bony abnormalities, and deficient beta-galactosidase. Synonym: sialidosis. (05 Mar 2000) |
| mongolian spot | <dermatology> A benign bluish or bruised-appearing birthmark that is usually located on the lower back or buttocks. More common in dark-skinned races and may persist for months to years. (27 Sep 1997) |
| white spot | Gray-white or white, rounded or irregularly shaped, slightly opaque patches or spots that are sometimes observed postmortem in the epicardium, especially in middle-aged or older persons; they result from fibrous thickening, and sometimes hyalinization, of the epicardium; similar lesions may also occur in the visceral layer of the peritoneum. Synonym: macula lactea, macula tendinea, tache blanche, tache laiteuse, tendinous spot, white spot. (05 Mar 2000) |
| white spot disease | Small discrete, white, waxy, indurated lesions due to localised degenerative changes in the fibrous tissue. Synonym: white spot disease. (05 Mar 2000) |
| corneal spot | A moderately dense opacity of the cornea. Synonym: corneal spot. (05 Mar 2000) |
| saccular spot | The oval neuroepithelial sensory receptor in the anterior wall of the saccule; hair cells of the neuroepithelium support the statoconial membrane and have terminal arborizations of vestibular nerve fibres around their bodies. Synonym: macula sacculi, saccular spot. (05 Mar 2000) |
| helminthosporium leaf spot | A plant disease affecting some grasses which is caused by parasitic fungi from the genus Helminthosporium and which appears as discoloured spots. (09 Oct 1997) |
| hot spot | <molecular biology> A particular area of DNA which is especially prone to spontaneous mutations or recombinations. (09 Oct 1997) |
| hypnogenic spot | A pressure-sensitive point on the body of certain susceptible persons, which, when pressed, causes the induction of sleep. (05 Mar 2000) |
| Soemmerring's spot | An oval area of the sensory retina, 3 by 5 mm, temporal to the optic disk corresponding to the posterior pole of the eye; at its centre is the central fovea, which contains only retinal cones. Synonym: area centralis, macula lutea, macular area, punctum luteum, Soemmerring's spot, yellow spot. (05 Mar 2000) |
| spongy spot | An area in the external acoustic meatus where a number of minute blood vessels enter from the mastoid bone. Synonym: spongy spot, zona vasculosa. (05 Mar 2000) |