placode


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placode

 [plak´ōd]
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).

plac·ode

(plak'ōd),
Local thickening in the embryonic ectodermal layer; the cells of the placode ordinarily constitute a primordial group from which a sense organ or ganglion develops.
[G. plakōdēs, fr. plax, anything flat or broad, + eidos, like]

plac·ode

(plak'ōd)
Local thickening in the embryonic ectodermal layer; the cells of the placode ordinarily constitute a primordial group from which a sense organ or ganglion develops.
[G. plakōdēs, fr. plax, anything flat or broad, + eidos, like]

placode

a plate-like embryonic structure from which a particular organ, such as the eye, develops.
References in periodicals archive ?
Thickening of the ectoderm, which is known as the otic placode, constitutes the embryological basis of the IE.
The protrusion forms in the dorsal wall of the aortic sac, which has a core derived from the second heart field, with only its outer layer derived from the cardiac neural crest,[7] which is defined as the neural crest residing between the otic placode and the third somite.
Similarly, lens formation begins in the third week of gestation as the "lens placode" and initial development concludes in the seventh week.
During stage HH16, Hey1 gene expression was maintained in the first three branchial clefts, the maxillary prominence primordium, the dorsal side of the mandibular prominence primordium, the ventral region of BA2 and BA3, the margins of the otic vesicle, and in the nasal placode (Figure 1, D).
Interestingly, SU5402 treatment at E12.5 only results in narrower tooth bud formation, indicating that FGF signaling takes part in epithelium stratification but not placode invagination [86, 87].
The cleft lip and palate defect occurs due to defect in the fusion of frontonasal, maxillary, and mandibular processes, while the proboscis lateralis occurs as a result of displacement of the nasal placode during the formation of the nose [1, 2].
Further, Pax6 is specifically expressed in the lens placode through a combination of activation by Sox2, Oct-1, and Foxe3 in the surface ectoderm and inhibition by TGF[beta] and Wnt signaling in the periocular neural crest [47-51].
Notably, the expression of Pax2 is one of the first indicators of otic placode induction, and it continues to be expressed in various regions of the ear throughout subsequent stages of development.
Since the embryonic migration of GnRH neurons from the nasal placode towards their final destination in the hypothalamus occurs in association with olfactory receptor neurons, the resulting phenotype includes anosmia in addition to HH.
At E2.5, we found that developing inner ear can be noticed by thickening of the ectodermal epithelium, otic placode. Invagination of such placode contributed to the otic cup closure and then the otic vesicle is completely formed (Brigande et al.; Sai & Ladher, 2015).
The main goal for prenatal repair of MMC is to achieve skin closure to prevent further damage of the placode and arrest the CSF leak.
The genetic locus for X-linked Kallmann syndrome has been assigned to be X p 22.3, where the KAL-1 gene encodes Anosmin 1, which plays a role in normal migration of both GnRH secreting neurons and axons of olfactory neurons from the olfactory placode to the brain, thus linking anosmia with hypogonadotropism.