A neurogenic placode is an area of thickening in the embryonic

Embryo

An embryo is a multicellular diploid eukaryote in its earliest stage of development, from the time of first cell division until birth, hatching, or germination...

 epithelial layer where some organ or structure later develops. The term usually refers to cranial placodes, peripheral nervous system

Peripheral nervous system

The peripheral nervous system consists of the nerves and ganglia outside of the brain and spinal cord. The main function of the PNS is to connect the central nervous system to the limbs and organs. Unlike the CNS, the PNS is not protected by the bone of spine and skull, or by the blood–brain...

 structures associated with the special senses

Special senses

In medicine and anatomy, the special senses are the senses that have specialized organs devoted to them:*vision *hearing and balance *smell *taste...

 and cranial ganglia. Placodes also develop in the formation of other structures, such as teeth and feathers.

Human

• The placodes associated with the special senses
  Special senses
  In medicine and anatomy, the special senses are the senses that have specialized organs devoted to them:*vision *hearing and balance *smell *taste...
  
   are:
  • The otic placode
    Otic placode
    In embryology, the otic placode is a thickening of the ectoderm on the outer surface of a developing embryo from which the ear develops. The ear, including both the vestibular system and the auditory system, develops from the otic placode beginning the third week of development...
    
    forms the otic pit and the otic vesicle, giving rise eventually to organs of hearing and equilibrium.
  • The lens placode
    Lens placode
    The Lens placode is a thickened portion of ectoderm which serves as the precursor to the lens.SOX2 and Pou2f1 are involved in its development.-External links:* http://cwx.prenhall.com/bookbind/pubbooks/martini10/chapter18/custom3/deluxe-content.html...
    
    under the direction of the optic vesicle gives rise to the lens of the eye.
  • The olfactory placode
    Nasal placode
    The nasal placode gives rise to the olfactory epithelium of the nose.The terms "nasal sac" or "nasal pit" are sometimes used to describe an intermediate structure arising between the placode and epithelium chronologically....
    
    (or nasal placode) gives rise to the olfactory epithelium
    Olfactory epithelium
    The olfactory epithelium is a specialized epithelial tissue inside the nasal cavity that is involved in smell. In humans, it measures about 1 square centimetre and lies on the roof of the nasal cavity about 7 cm above and behind the nostrils...
    
     of the nose
    Human nose
    The visible part of the human nose is the protruding part of the face that bears the nostrils. The shape of the nose is determined by the ethmoid bone and the nasal septum, which consists mostly of cartilage and which separates the nostrils...
    
    .

• The trigeminal placode consists of ophthalmic and maxillomandibular parts.

• The epipharyngeal placode

• The dorsolateral placode

Non-human species

• The lateral line placodes (in aquatic vertebrates) give rise to the lateral line system.

• The profundal placodes