| disease transmission, vertical | The transmission of infectious disease or pathogens from one generation to another. It includes transmission in utero or intrapartum by exposure to blood and secretions, and postpartum exposure via breastfeeding. (12 Dec 1998) |
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| duplex transmission | The passage of impulses in both directions through a nerve trunk. (05 Mar 2000) |
| iatrogenic transmission | Transmission of infectious agents due to medical interference (e.g., transmission by contaminated needles). (05 Mar 2000) |
| indirect transmission | <epidemiology> Transmission of a parasite through an indirect life cycle. (05 Dec 1998) |
| transmission | 1. <microbiology, physiology> A passage or transfer, as of a disease from one individual to another or of neutral impulses from one neuron to another. 2. <genetics> The communication of inheritable qualities from parent to offspring (18 Nov 1997) |
| transmission breakpoint | <epidemiology> A critical average worm burden below which the mating frequency is too low to maintain a dioecious parasite species. (05 Dec 1998) |
| transmission electron microscopy | <technique> Those forms of electron microscopy in which electrons are transmitted through the object to be imaged, suffering energy loss by diffraction and to a small extent by absorption. Acronym: TEM (18 Nov 1997) |
| transmission threshold | <epidemiology> Occurs for a parasite when the basic reproductive rate Ro is equal to 1. Below this threshold level the disease is unable to maintain itself within the host population. Typically, for directly transmitted parasites there is a transmission threshold for the host population size. (05 Dec 1998) |
| transovarial transmission | Passage of parasites or infective agents from the maternal body to eggs within the ovaries; commonly used to describe certain arthropods, to explain the ability of larvae of the next generation to transmit disease pathogens, as with the infection of larval mites or ticks with rickettsiae or viruses. (05 Mar 2000) |
| transstadial transmission | Passage of a microbial parasite, such as a virus or rickettsia, from one developmental stage (stadium) of the host to its subsequent stage or stages, particularly as seen in mites. See: transovarial transmission. (05 Mar 2000) |
| binocular microscope | <instrument, microscopy> A microscope fitted with double eyepieces for vision with both eyes. The purpose in dividing the same image from a single objective of the usual compound micro-scope is to reduce eyestrain and muscular fatigue which may result from monocular, high-power microscopy. The purpose in obtaining a different image for each of two oculars is to provide stereoscopy by means of two different angles of view. There are two kinds of stereoscopic microscopes: binobjective (Greenough) older type and monobjective (common main objective) newer type. (See stereo microscope, Greenough microscope, etc.) (05 Aug 1998) |
| Rheinberg microscope | <instrument> A modified form of dark-field microscope in which the central opaque stop in the condenser is replaced by a coloured filter, producing a background of contrasting colour against which the specimen is illuminated. (05 Mar 2000) |
| Greenough microscope | <instrument, microscopy> One of two kinds of stereomicroscopes with two separate compound microscopes, one for each eye, focused on the same object. The other kind has a common main objective. See: binocular microscope. (05 Aug 1998) |
| phase-contrast microscope | <instrument> A specially constructed microscope that has a special condenser and objective containing a phase-shifting ring whereby small differences in index of refraction are made visible as intensity or contrast differences in the image; particularly useful for examining structural details in transparent specimens such as living or unstained cells and tissues. (05 Mar 2000) |
| microscope | <instrument> A piece of laboratory equipment that is used to magnify small things that are too small to be seen by the naked eye, or too small for the details to be seen by the naked eye, so that their finer details can be seen and studied. Examples are the light (or optical) microscope, electron microscope, X-ray microscope, and acoustic microscope. (09 Oct 1997) |