- During 5th week of intrauterine life rapidly proliferating mesenchymal swelling, appear on the internal aspect of mandibular arch, known as lateral lingual swelling.
- A small median projection arises between lateral lingual swelling, the tuberculum impar.
- These 3 swelling arises from the 1st pharyngeal arch.
- Caudal to this is the copula or hypobranchial eminence, is formed by mesoderm of 2nd, 3rd, part of 4th arch and contributes to tongue structure.
- The point at which the 1st and 2nd arches merge is marked by formation of foramen caecum, just behind the sulcus terminalis (a `v` shaped groove).
I. Foramen caecum gives rise to thyroid.
II. Lingual swelling gives rise to anterior 2/3 of tongue.
III. Copula gives rise to posterior 1/3 of tongue.
- By 11th weeks of foetal life papillae of tongue are seen.
- By 12th weeks taste buds are seen in the circumvallate papillae.
- By 14th weeks taste buds can be observed in the fungiform papillae.