ANAT2341 Lab 6 - Fetal

From Embryology
Lab 6: Introduction | Trilaminar Embryo | Early Embryo | Late Embryo | Fetal | Postnatal | Abnormalities | Online Assessment

Fetal Growth

<html5media height="480" width="400">File:fetal growth.mp4</html5media>
Links: Fetal Development Movie | MP4 version | Fetal Development

In this cartoon movie of fetal growth, observe the changing relative sizes of the head, body and limbs.

Then consider fetal skeletal changes occurring within the head associated with ossification processes and palate development.

Finally consider fetal changes that are occurring in auditory pathway.

Fetal Head Growth

Fetal head growth circumference graph01.jpg

Head Circumference Growth (both gestational and post-fertilisation ages are shown)

Skull Ossification

These are 2 views of the same 12 week 92 mm CRL human fetus head, double stained to show both cartilage (blue) and newly-formed bone (red). The head undergoes two different forms of ossification (endochondral and intramembranous) in separate regions of the skull.

Lateral view (external) Medial view (internal)
Fetal head lateral.jpg Fetal head medial.jpg
Note the distribution of new bone formation by intramembranous ossification in the plates of the cranial vault, temporal bone, orbit, upper jaw (maxilla) and lower jaw (mandible) regions. Bony regions in the lower jaw (mandible) region also show spaces where tooth formation is occurring. Note the distribution of cartilage from the nasal region through the base of the skull showing endochondral ossification, also occuring in the atlas/axis (with new bone forming). See also the original Meckel's cartilage within the newly forming bony mandible.

Skull superior.gif

Late Fetal Skull

Mandible Ossification

Ossification centre.jpg Intramembranous ossification centre.jpg


The cartilage template of the mandible and the base of the skull are replaced by early bone development.

Fetal head section.jpg Fetal head section 01.jpg

Selected midline medial head view showing key features of head musculoskeletal and neurological development.

Note extensive nasal cartilage, nasal conchae, pituitary, secondary palate, oral cavity, tongue, mandible, hyoid, choana, oropharynx.

Also note the developing tongue musculature and its mandibular attachment site.

Note that the cranial vault, the portion of the skull enclosing the brain, ossifies by a unique bone formation process, intramembranous ossification.

Because the head contains many different structures also review notes on Special Senses (eye, ear, nose), Respiration (pharynx), Integumentary (Teeth), Endocrine (thyroid, parathyroid, pituitary) and Musculoskeletal (tongue, skull).

Palate Development

Early Fetal Palate

Secondary palate formation is the growth of the palatal shelves towards the midline.

Inferior view Anterior view
<html5media height="400" width="400">File:Palate_001.mp4</html5media> <html5media height="400" width="400">File:Palate_002.mp4</html5media>
Palate 001 icon.jpg Palate 002 icon.jpg
Early Fetal Palate
Palate 001 icon.jpg
 ‎‎Palate (oral view)
Page | Play
Palate 002 icon.jpg
 ‎‎Palate (front view)
Page | Play
Palate Overview


  • week 4 - pharyngeal arch formation, first pharngeal arch contributes mandible and maxilla.
  • week 6 - 7 - primary palate formation maxillary processes and frontonasal prominence.


  • week 9 - secondary palate shelves fuse, separating oral and nasal cavities.

Week 10 Gestational Age (GA week 12)

Fetal week 10 hard palate 07.jpg

hard palate

Fetal week 10 soft palate 03.jpg

soft palate

Lab 6: Introduction | Trilaminar Embryo | Early Embryo | Late Embryo | Fetal | Postnatal | Abnormalities | Online Assessment

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Cite this page: Hill, M.A. (2024, April 22) Embryology ANAT2341 Lab 6 - Fetal. Retrieved from

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© Dr Mark Hill 2024, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G