BGDB Face and Ear - Late Embryo

Week 6

Primary Palate

Beginning week 6 there is fusion of the upper lip.
Formed by the maxillary prominences of of the first pharyngeal arch and the frontonasal prominence.
Failure of this embryonic process leads to cleft lip.

Week 6 (stage 16)
Week 6 (stage 17)
Week 7 (stage 18)
Week 7 (stage 19)

Above images show face development through week 6 to week 7 (1mm scale markings).

The animation shows the early fusion of the primary palate in the human embryo between stage 17 and 18, going from an epithelial seam to the mesenchymal bridge.

Face Development Movie | MP4 movie

This animation shows a ventral view of development of the human face from approximately week 5 through to neonate.

The separate embryonic components that contribute to the face have been colour coded.

Frontonasal Prominence - frontal central (white)
Frontonasal Prominence - Lateral nasal (purple)
Frontonasal Prominence - Medial nasal (green)
Pharyngeal Arch 1 - Maxillary prominence (yellow)
Pharyngeal Arch 1 - Mandibular prominence (orange)
Stomodeum (black)

Week 8

Oral Cavity (stage 23)
Floor
Floor (labeled)
Roof
Roof (labeled)

Selected Head Images: B4 - Choroid Plexus | B5 - Cochlea | B6 - Cochlea

Palate

The dark "pear-shaped" central structure at the top is the developing tongue. The two pale regions either side are the palatal shelves, note that they have not yet fused in the midline (failure of this process is cleft palate).

Hearing

Growth and stages of differentiation of the human membranous labyrinth.

Behind that a pale cartilagenous region (that later ossifies) encloses the structuctures of the inner ear, beside which middle ear bones are forming. On the righthand side of the head the external ear is visible. The lower half of the image shows the developing brainstem with a large ventricular space occupied in part by an extensive choroid plexus (manufacturer of cerebrospinal fluid).

Embryonic External Ear

Shown below are the changes in external ear development between week 5 to week 8. Development changes from a series of 6 hillocks on arch 1 and arch 2 (week 5) to a structure resembling the adult ear (week 8).

Additional Information

Additional Information - Content shown under this heading is not part of the material covered in this class. It is provided for those students who would like to know about some concepts or current research in topics related to the current class page.

External Auditory Meatus Timeline

Time	EAM Appearance
Embryonic period	Ectodermal cells proliferate and fill the entire lumen forming a meatal plug
10 weeks	Meatal plug extends in a disc-like fashion. In the horizontal plane the meatus is boot-shaped with a narrow neck and the sole of the meatal plug spreading widely to form the future tympanic membrane medially. Proximal portion of the neck starts to be resorbed.
13 weeks	Disc-like plug innermost surface in contact with the primordial malleus, contributes to the formation of the tympanic membrane.
16.5 week	Meatus is fully patent throughout its length, lumen is still narrow and curved.
18 week	Meatus is already fully expanded to its complete form.

Based on data from PMID 1441991

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Cite this page: Hill, M.A. (2024, April 19) Embryology BGDB Face and Ear - Late Embryo. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/BGDB_Face_and_Ear_-_Late_Embryo

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