Placode

(redirected from Olfactory placode)
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placode

[′pla‚kōd]
(embryology)
A platelike epithelial thickening, frequently marking, in the embryo, the anlage of an organ or part.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Placode

 

the rudiment of a sense organ or ganglion in humans, vertebrates, and some invertebrates. Placodes are paired thickenings of the outermost embryonic germ layer, the ectoderm; they arise as the nervous system is laid down in the early stages of embryogeny. In vertebrates, placodes give rise to the olfactory organ, the crystalline lens of the eye, the inner ear, the auditory ganglion, and the ganglia of the facial, glossopharyngeal, and vagus nerves. In cyclostomes, fishes, and many amphibians, placodes give rise to the lateral-line organs in addition to the aforementioned structures.

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.
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