Development of Face
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The stomodeum or the primitive buccal cavity is formed by the formation of the cranial and lateral foldings and subsequent cranial flexures. It is separated from the pharyngeal cavity by the oropharyngeal membrane which breakdown following the fusion of the left and right mandibular processes. During the foetal development, the stomodeum becomes greatly elongated as a result of the growth of the maxillary, mandibular and nasal process.
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Neural crest mesenchymal cells initially located over the dorsal and rostral surfaces of the procencephalon are brought to the rostral and ventral surfaces of the head as a result of >90 ° cranial flexure. This population of cells called the frontonasal mesenchyme, will form the forehead and nasal regions of the face. At the early stage, the fronto nasal mesenchyme, will form the forehead and nasal regions of the face. At the early stage, the fronto nasal process represents forehead. A thickening of ectoderm on each side o this process forms the olfactory placode (nasal placode).
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Each nasal placode invaginates to form the nasal pit which deepens and subsequently contacts the roof of the stomodeum. The nasal pit is circumscribed by two swellings, the medial nasal process and the lateral nasal process derived from fronto nasal mesenchyme.The area between the two medial nasal processes extending dorsally over the forebrain is the frontal prominence. The line of fusion of the two medial nasal process is the philtrum.
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Each medial nasal process unites with the maxillary process of the respective side to form the upper jaw and cheek regions. The lateral nasal process fuse with the maxillary process closing the oculo-nasal sulcus and thus completing the socket. The lateral nasal processes become the sides and wings of the nose.
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The two mandibular processes unite in front to form the lower jaw. The bifurcation of maxillary and mandibular processes is reduced by the establishment of the lips and cheeks forming the rima oris.
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Last modified: Thursday, 15 December 2011, 5:50 AM