The nasal placode (or olfactory placode) gives rise to the

olfactory epithelium The olfactory epithelium is a specialized epithelial tissue inside the nasal cavity that is involved in smell. In humans, it measures 9 cm2 and lies on the roof of the nasal cavity about 7 cm above and behind the nostrils. The olfactory ...

of the

nose A nose is a protuberance in vertebrates that houses the nostrils, or nares, which receive and expel air for respiration alongside the mouth. Behind the nose are the olfactory mucosa and the sinuses. Behind the nasal cavity, air next pass ...

. Two nasal placodes arise as thickened

ectoderm The ectoderm is one of the three primary germ layers formed in early embryonic development. It is the outermost layer, and is superficial to the mesoderm (the middle layer) and endoderm (the innermost layer). It emerges and originates from the o ...

from the

frontonasal process The frontonasal process, or frontonasal prominence is one of the five swellings that develop to form the face. The frontonasal process is unpaired, and the others are the paired maxillary prominences, and the paired mandibular prominences. During t ...

. They give rise to the

, the

philtrum The philtrum ( la, philtrum from Ancient Greek ''phíltron,'' lit. "love charm"), or medial cleft, is a vertical indentation in the middle area of the upper lip, common to therian mammals, extending in humans from the nasal septum to the tuber ...

of the upper lip, and the primary palate.

Development

During the fifth week of

human embryonic development Human embryonic development, or human embryogenesis, is the development and formation of the human embryo. It is characterised by the processes of cell division and cellular differentiation of the embryo that occurs during the early stages of d ...

the placodes increase in size. In the sixth week of development the centre of each placode grows inwards to form the two nasal pits. The invaginations will give rise to the olfactory epithelium that lines the roof of the

nasal cavity The nasal cavity is a large, air-filled space above and behind the nose in the middle of the face. The nasal septum divides the cavity into two cavities, also known as fossae. Each cavity is the continuation of one of the two nostrils. The nasal ...

. The nasal pits are oval shaped and they leave a raised margin which is divided into a medial nasal process and a lateral nasal process. The medial and lateral nasal process of each placode gives rise to the

, the

of the upper lip and the primary

palate The palate () is the roof of the mouth in humans and other mammals. It separates the oral cavity from the nasal cavity. A similar structure is found in crocodilians, but in most other tetrapods, the oral and nasal cavities are not truly s ...

References

External links

* https://web.archive.org/web/20130509194720/http://embryology.med.unsw.edu.au/Notes/week4_3.htm#nose * https://web.archive.org/web/20060925080120/http://www.ana.ed.ac.uk/database/humat/notes/embryo/sensory/nose.htm Animal developmental biology Embryology {{Anatomy-stub

Development

See also

References

External links