Local thickening in the embryonic ectoderm layer; the cells of the p. ordinarily constitute a primordial group from which a sense organ or ganglion develops. [G. plakodes, fr. plax, anything flat or broad, + eidos, like]
- auditory placodes SYN: otic placodes.
- epibranchial placodes ectodermal thickenings associated with the more dorsal parts of the embryonic branchial arches; their cells contribute to formation of the cranial ganglia, including those of nerves V, VII, IX, and X.
- lens placodes paired ectodermal placodes that become invaginated to form the embryonic lens vesicles. SYN: optic placodes.
- nasal placodes SYN: olfactory placodes.
- olfactory placodes paired ectodermal placodes that come to lie in the bottom of the olfactory pits as the pits are deepened by the growth of the surrounding medial and lateral nasal processes. SYN: nasal placodes.
- optic placodes SYN: lens placodes.
- otic placodes paired ectodermal placodes that sink below the general level of the superficial ectoderm to form the auditory vesicles. SYN: auditory placodes.

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plac·ode 'pla-.kōd n a platelike thickening of embryonic ectoderm from which a definitive structure develops <ear \placode> see LENS PLACODE, OLFACTORY PLACODE

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any of the thickened areas of ectoderm in the embryo that will develop into nerve ganglia or the special sensory structures of the eye, ear, or nose.

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plac·ode (plakґōd) [Gr. plax plate + eidos form] a platelike structure, especially a thickened plate of ectoderm in the early embryo, from which a sense organ develops.

Medical dictionary. 2011.

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  • placode — [plakɔd] n. f. ÉTYM. XXe; de placo , et du grec eidos « forme ». ❖ ♦ Embryol. Chacun des épaississements de l ectoderme dont dériveront les organes des sens et les ganglions nerveux. || Placode auditive, olfactive, optique …   Encyclopédie Universelle

  • Placode — A placode is an area of thickening in the embryonic epithelial layer where some organ or structure later develops. The term usually refers to cranial placodes, peripheral nervous system structures associated with the special senses and cranial… …   Wikipedia

  • placode — ˈplaˌkōd noun ( s) Etymology: International Scientific Vocabulary plac + ode : a platelike thickening of embryonic ectoderm from which a definitive structure develops ear placode olfactory placode see lens placode …   Useful english dictionary

  • placode — a thickened or plate like region within an epithelium …   Dictionary of ichthyology

  • placode — Area of thickened ectoderm in the embryo from which a nerve ganglion, or a sense organ will develop …   Dictionary of molecular biology

  • placode — /plak ohd/, n. Embryol. a local thickening of the endoderm in the embryo, that usually constitutes the primordium of a specific structure or organ. [1905 10; < Gk plak (s. of pláx) something flat, tablet + ODE1] * * * …   Universalium

  • placode — noun A platelike thickening of the epithelial layer of an embryo from which an organ, especially a sense organ, develops …   Wiktionary

  • placode — pla·cò·de s.m. TS embriol. nei Vertebrati, ispessimento discoidale dell ectoderma, nella zona cefalica dell embrione, da cui derivano gli organi sensoriali {{line}} {{/line}} DATA: 1958. ETIMO: dal gr. plakōdēs piatto …   Dizionario italiano

  • placode — pl.m. placodi …   Dizionario dei sinonimi e contrari

  • placode — n. thickening of endodermic tissue, initial stage in organ formation (Embryology) …   English contemporary dictionary

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