| monochorial twins | Identical twins, twins which are the result of a single zygote (fertilized egg) splitting into two cell masses and becoming two individuals. The twins are genetically identical and are always of the same sex (both males or both females). Compare: dizygotic twins. (09 Oct 1997) |
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| monochorionic | Relating to or having a single chorion; denoting monovular twins. Synonym: monochorial. (05 Mar 2000) |
| monochorionic diamniotic placenta | The placenta(s) of a twin pregnancy; if dizygotic, the placenta's may be separate or fused, the latter retaining two amniotic and two chorionic sacs (dichorionic diamniotic placenta); if monozygotic, the placenta may be a (05 Mar 2000) |
| monochorionic monoamniotic placenta | Depending on the stage at which twinning took place; if twinning occurs early, there may be a fused placenta with two chorionic and two amniotic membranes. Alternative form: monochorionic diamniotic placenta (05 Mar 2000) |
| monochroic | <microscopy> All objects in a group (electrons, light, X-rays etc.) have the same energy or wavelength. (05 Aug 1998) |
| monochromasia | A severe congenital deficiency in colour perception, often associated with nystagmus and reduced visual acuity. Synonym: achromatic vision, monochromasia, monochromasy, monochromatism. Origin: G. A-priv. + chroma, colour, + opsis, vision (05 Mar 2000) |
| monochromasy | A severe congenital deficiency in colour perception, often associated with nystagmus and reduced visual acuity. Synonym: achromatic vision, monochromasia, monochromasy, monochromatism. Origin: G. A-priv. + chroma, colour, + opsis, vision (05 Mar 2000) |
| monochromatic | <microscopy> All objects in a group (electrons, light, X-rays etc.) have the same energy or wavelength. (05 Aug 1998) |
| monochromatic aberration | A defect in an optical image arising because of the nature of lenses; the main types are spherical, coma, curvature, and distortion aberration, and astigmatism of oblique pencils. (05 Mar 2000) |
| monochromatic light | <microscopy> Light composed of one wavelength. It may be obtained by the use of a laser or by gaseous discharge tubes in combination with proper filters. An approximation is obtained by interference filters or monochromators. (05 Aug 1998) |
| monochromatic rays | Light ray's or ionizing radiation of a very narrow band of wavelengths (ideally, of a single wavelength). Compare: photopeak, characteristic radiation. (05 Mar 2000) |
| monochromatism | 1. The state of having or exhibiting only one colour. Synonym: achromatopsia. Origin: mono-+ G. Chroma, colour (05 Mar 2000) |
| monochromatophil | Monochromatophile 1. Taking only one stain. 2. A cell or any histologic element staining with only one kind of dye. Synonym: monochromophil, monochromophile. Origin: mono-+ G. Chroma, colour, + philos, fond (05 Mar 2000) |
| monochromator | <microscopy> A light-dispersing instrument which is used to obtain light of substantially one wavelength, or at least of a very narrow band of the spectrum. The light is apt to be weak because of its purity. The use of monochromatic light filters is usually adequate for microscopical work. (05 Aug 1998) |
| monochromic | <microscopy> All objects in a group (electrons, light, X-rays etc.) have the same energy or wavelength. (05 Aug 1998) |