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an oval area of thickened ectoderm on either ventrolateral surface of the head of the early embryo, constituting the first indication of the olfactory organ.
a platelike structure, especially a thickening of the ectoderm marking the site of future development in the early embryo of an organ of special sense, e.g. the auditory placode (ear), lens placode (eye) and olfactory placode (nose).
the ectodermal thickening which develops into the lens vesicle and later the lens.
one of a pair of ectodermal thickenings which are the forerunners of the external nares and nasopharyngeal epithelium.
an ectodermal thickening of the embryo which ultimately provides the sensory nerves for the olfactory region of the nasal mucosa.
one of the pair of ectodermal thickenings in the vertebrate embryo which invaginates and is a major contributor to the internal ear.