| labyrinthotomy | Incision into the labyrinth. Origin: Labyrinth + G. Tome, incision (05 Mar 2000) |
|---|---|
| labyrinthus | Synonym: convoluted part of kidney lobule. Origin: L. Fr. G. Labyrinthos, labyrinth (05 Mar 2000) |
| labyrinthus cochlearis | The content of the cochlea including the portion of the membranous labyrinth containing the spiral organ (cochlear duct) and the perilymphatic channels (scalae) which lie on either side. Synonym: labyrinthus cochlearis, organ of hearing. (05 Mar 2000) |
| labyrinthus ethmoidalis | A mass of air cells with thin bony walls forming part of the lateral wall of the nasal cavity; the cells are arranged in three groups, anterior, middle, and posterior, and are closed laterally by the orbital plate which forms part of the wall of the orbit. Synonym: labyrinthus ethmoidalis, ectethmoid, ectoethmoid, lateral mass of ethmoid bone. (05 Mar 2000) |
| labyrinthus membranaceus | A complex arrangement of communicating membranous canaliculi and sacs, filled with endolymph and surrounded by perilymph, suspended within the cavity of the bony labyrinth; its chief divisions are the cochlear labyrinth and the vestibular labyrinth. Synonym: labyrinthus membranaceus. (05 Mar 2000) |
| labyrinthus osseus | A series of cavities (cochlea, vestibule, and saemicircular canals) contained within the otic capsule of the petrous portion of the temporal bone; the bony labyrinth is filled with perilymph, in which the delicate, endolymph-filled membranous labyrinth is suspended. Synonym: labyrinthus osseus, osseous labyrinth. (05 Mar 2000) |
| labyrinthus vestibularis | The portion of the membranous labyrinth located within the saemicircular canals and the vestibule of the osseous labyrinth. It is surrounded with perilymph and involved with vestibular functions. Synonym: labyrinthus vestibularis. (05 Mar 2000) |
| lac | A resinous substance produced mainly on the banyan tree, but to some extent on other trees, by the Coccus lacca, a scale-shaped insect, the female of which fixes herself on the bark, and exudes from the margin of her body this resinous substance. Stick-lac is the substance in its natural state, incrusting small twigs. When broken off, and the colouring matter partly removed, the granular residuum is called seed-lac. When melted, and reduced to a thin crust, it is called shell-lac or shellac. Lac is an important ingredient in sealing wax, dyes, varnishes, and lacquers. Ceylon lac, a resinous exudation of the tree Croton lacciferum, resembling lac. Lac dye, a scarlet dye obtained from stick-lac. Lac lake, the colouring matter of lac dye when precipitated from its solutions by alum. Mexican lac, an exudation of the tree Croton Draco. Origin: Per. Lak; akin to Skr. Laksha: cf. F. Lague, It. & NL. Lacca. Cf. Lake a colour, Lacquer, Litmus. Source: Websters Dictionary (01 Mar 1998) |
| Lac operon | Group of adjacent and coordinately controlled genes concerned with the metabolism of lactose in E. Coli. The lac operon was the first example of a group of genes under the control of an operator region to which a lactose repressor binds. When the bacteria are transferred to lactose containing medium, allolactose (which forms by transglycosylation when lactose is present in the cell) binds to the repressor, inhibits the binding of the repressor to the operator and allows transcription of mRNA for enzymes involved in galactose metabolism and transport across the membrane (_ galactosidase, galactoside permease and thiogalactoside transacetylase). (18 Nov 1997) |
| lac sulfuris | Sublimed sulfur boiled with lime water, the lime being removed from the precipitate by washing with diluted hydrochloric acid; used in preparing sulfur ointment and in the treatment of various skin disorders. Synonym: lac sulfuris, milk of sulfur. (05 Mar 2000) |
| lac vaccinum | Cow's milk. (05 Mar 2000) |
| lacca | A resinous excretion of an insect, Laccifer (Tachardia) lacca (family Coccidae). The insects suck the juice of various resiniferous Asiatic (chiefly Indian) trees and excrete and deposit "stick-lac." shellac softens at a low temperature. It has many nonmedicinal uses and is also used to coat confections and tablets and in dental materials, e.g., impression compound and denture base plates. Synonym: lacca. (05 Mar 2000) |
| laccase | <enzyme> An enzyme oxidizing benzenediols to semiquinones with O2. Synonym: monophenol monooxygenase, phenol oxidase, phenolase, polyphenol oxidase, urushiol oxidase. (05 Mar 2000) |
| laccic | <chemistry> Pertaining to lac, or produced from it; as, laccic acid. Origin: Cf. F. Laccique. Source: Websters Dictionary (01 Mar 1998) |
| laccin | <chemistry> A yellow amorphous substance obtained from lac. Origin: Cf. F. Laccine. Source: Websters Dictionary (01 Mar 1998) |