Development of Important Structures FMGE

FMGE Important Topics
[Type the document subtitle]
Virues




DEVELOPMENT OF FACE

The face begins to develop at the end of fourth week of IUL from five swellings /processes
that form around primitive mouth(stomodaeum).These processes are:

 Single frontonasal process
 Paired maxillary processes
 Paired mandibular processes
Frontonasal process forms forehead, external nose, nasal cavity, nasal septum &
philtrum of the upper lip
The two maxillary processes grow medially below developing eyes and fuse with the lateral
nasal process to form the lateral part of upper lip and upper part of cheek.

The two mandibular processes fuse to form the lower lip and lower part of cheek.



DEVEPMENT OF THYROID GLAND

 The Thyroid gland begins to develop during the third week of of IUL from
endodermal diverticulum –the thyroglossal duct in the midline of primitive pharynx
between the tuberculum impar and copula.
 The diverticulum grows down in the midline into the neck .Its tip soon bifurcates.
 Proliferation of the cells of this bifid end gives rise to the two lobes of the thyroid
gland.
 The Parafollicular or C cells of the thyroid gland develop from neural crest cells of the
caudal pharyngeal complex(Ultimobrachial body) formed by fusion of fourth and
fifth pharyngeal pouches.