| loculation syndrome | <syndrome> An alteration in the cerebrospinal fluid, which is yellowish and coagulates spontaneously in a few seconds after withdrawal, owing to its greatly increased protein (albumin and globulin) content; noted in loculated portions of the subarachnoid space isolated from spinal fluid circulation by an inflammatory or neoplastic obstruction. Synonym: loculation syndrome. (05 Mar 2000) |
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| locule | A compartment of an anther or an ovary. (09 Oct 1997) |
| loculicidal | Of the dehiscence of a fruit, along lines coinciding with the centres of loculi. Compare: septicidal. (09 Oct 1997) |
| loculous | <botany> Divided by internal partitions into cells, as the pith of the pokeweed. Origin: L. Loculosus. See Loculament. Source: Websters Dictionary (01 Mar 1998) |
| loculus | An enclosed compartment within an organ for example an ovary, an anther. (09 Oct 1997) |
| locum tenant | A temporary substitution of one physician by another. Synonym: locum tenens. Origin: partial anglicization of locum tenens (05 Mar 2000) |
| locum tenens | Synonym: locum tenant. Origin: L. One holding a place (05 Mar 2000) |
| locus | <genetics> The site in a linkage map or on a chromosome where the gene for a particular trait is located. Any one of the alleles of a gene may be present at this site. (18 Nov 1997) |
| locus ceruleus | A shallow depression, of a blue colour in the fresh brain, lying laterally in the most rostral portion of the rhomboidal fossa near the cerebral aqueduct; it lies near the lateral wall of the fourth ventricle and consists of about 20,000 melanin-pigmented neuronal cell bodies whose norepinephrine-containing axons have a remarkably wide distribution in the cerebellum as well as in the hypothalamus and cerebral cortex. Synonym: substantia ferruginea, locus cinereus, locus ferrugineus. (05 Mar 2000) |
| locus cinereus | A shallow depression, of a blue colour in the fresh brain, lying laterally in the most rostral portion of the rhomboidal fossa near the cerebral aqueduct; it lies near the lateral wall of the fourth ventricle and consists of about 20,000 melanin-pigmented neuronal cell bodies whose norepinephrine-containing axons have a remarkably wide distribution in the cerebellum as well as in the hypothalamus and cerebral cortex. Synonym: substantia ferruginea, locus cinereus, locus ferrugineus. (05 Mar 2000) |
| locus coeruleus | Bluish region in the superior angle of the fourth ventricle floor, corresponding to melanin-like pigmented nerve cells which lie lateral to the ponto-mesencephalic central gray (griseum centrale). It is also known as nucleus pigmentosus pontis, locus cinereus, and locus ferrugineus. (12 Dec 1998) |
| locus control region | A regulatory region first identified in the human beta-globin locus but subsequently found in other loci. The region is believed to regulate transcription by opening and remodeling chromatin structure. It may also have enhancer activity. (12 Dec 1998) |
| locus ferrugineus | A shallow depression, of a blue colour in the fresh brain, lying laterally in the most rostral portion of the rhomboidal fossa near the cerebral aqueduct; it lies near the lateral wall of the fourth ventricle and consists of about 20,000 melanin-pigmented neuronal cell bodies whose norepinephrine-containing axons have a remarkably wide distribution in the cerebellum as well as in the hypothalamus and cerebral cortex. Synonym: substantia ferruginea, locus cinereus, locus ferrugineus. (05 Mar 2000) |
| locus minoris resistentiae | A place of less resistance, in latin. For example, a damaged heart valve may act as a locus minoris resistentiae where bacteria released into the blood stream (bacteraemia) tend to settle. (12 Dec 1998) |
| locus niger | A large cell mass, crescentic on transverse section, extending forward over the dorsal surface of the crus cerebri from the rostral border of the pons into the subthalamic region; it is composed of a dorsal stratum of closely spaced pigmented (i.e., melanin-containing) cells, the pars compacta, and a larger ventral region of widely scattered cells, the pars reticulata; the pars compacta in particular includes numerous cells that project forward to the striatum (caudate nucleus and putamen) and contain dopamine, which acts as the transmitter substance at their synaptic endings; other, apparently non-dopaminergic cells of the substantia nigra project to a rostral part of the ventral nucleus of thalmus, the middle layers of the superior colliculus and to restricted parts of the reticular formation of the midbrain; the nigrostriatal projection is reciprocated by a massive striatonigral fibre system with multiple neurotransmitters, chief among which is gamma-aminobutyric acid (GABA); substantia n. Receives smaller afferent projections from the subthalamic nucleus, the lateral segment of the globus pallidus, the dorsal nucleus of the raphe and the pedunculopontine nucleus of the midbrain. The pars reticulata forms part of the output system for the striate body. The substantia n. Is involved in the metabolic disturbances associated with Parkinson's disease and Huntington's disease. Synonym: locus niger, nucleus niger, Soemmerring's ganglion. (05 Mar 2000) |