| Frontonasal process | |
|---|---|
 Under surface of the head of a human embryo about twenty-nine days old. (Frontonasal process labeled at center left.) | |
| Details | |
| Precursor | Ectoderm |
| Identifiers | |
| TE | process_by_E5.3.0.0.0.0.6 E5.3.0.0.0.0.6 |
| Anatomical terminology | |
Thefrontonasal process, orfrontonasal prominence is one of the five swellings that develop to form the face. The frontonasal process is unpaired, and the others are the pairedmaxillary prominences, and the pairedmandibular prominences. During the fourth week ofembryonic development, an area of thickenedectoderm develops, on each side of the frontonasal process called thenasal placodes or olfactory placodes, and appear immediately under theforebrain.[1]
By invagination these areas are converted into twonasal pits, which indent the frontonasal prominence and divide it into medial and lateral nasal processes.[2]
Themedial nasal process (nasomedial) on the inner side of each nasal pit merge into theintermaxillary segment and form theupper lip, crest, and tip of thenose.[1] The medial nasal processes merge with the maxillary prominences. Thelateral nasal process from each side merge to form thealae of thenose.[1]
Failure to fuse can cause acleft lip.[1]
There is some evidence that development involvesSonic hedgehog andFibroblast growth factor 8.[3]
This article incorporates text in thepublic domain frompage 67 of the 20th edition ofGray's Anatomy(1918)
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