Paper - A model of the left half of the human mandible at the 17 mm CRL stage
|Embryology - 25 May 2020 Expand to Translate|
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Fawcett E. A model of the left half of the human mandible at the 17 mm CRL stage. (1930) J Anat Physiol. 47(2): 225-34. PMID:17104287 | PMC1250145
Week 6 - Intramembranous ossification center develops lateral to Meckel's cartilage.
Week 7 - Coronoid process begins differentiating.
Week 8 - Coronoid process fuses with main mandibular mass.
Week 10 (approx) - Both condylar and coronoid processes are recognizable and anterior portion of Meckel's cartilage begins to ossify.
Weeks 12-14 - Secondary cartilages for the condyle, coronoid, and symphysis appear.
Weeks 14-16 - Deciduous tooth germs start to form.
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A Model of the left half of the Human Mandible at the 17 mm CRL stage
By Professor Fawcett, M.D., F.R.S.
The sections from which this model was made were stained with Mallory’s stain, the most delicate known to me for bone. Fig. 1 shows the ossiﬁed mandible (M) as well as many other structures, e.g. Meckel’s cartilage, which is partially chondriﬁed (M C1) and towards its anterior end unchondriﬁed (M C2); the tongue (T) is also shown near its tip for topographical purposes: ﬁnally, the associated nerves, e.g. the mandibular (MN), the lingual (LN) with the submaxillary ganglion (SG), the inferior dental (I DN ), and the mental nerves (MN), are. introduced.
Fig. 1. Reconstruction of left mandible and annexes of a 17 millimetre human embryo viewed from above.
During the drawing for the production of the necessary wax plates a careful lookout was kept for tooth buds, but none were found. Furthermore, no sign of an incisive branch of the inferior dental nerve occurred, so the true termination of the inferior dental nerve would appear to be in the mental nerve and not a bifurcation into mental and incisive branches.
The mandible has ossiﬁed in the interval between the mental nerve and the unchondriﬁed part of Meckel’s cartilage, and it reaches from not far from the middle line to just beyond the mental nerve, which is lodged in a groove on the upper margin of the bone. The groove is the mental groove (MG).
The bone is a simple plate of bone with no processes. Meckel’s cartilage is unchondriﬁed from the front, back to the region of the mental groove.
The embryo from which this model was made I owe to the kindnessof my colleague, Prof. D. C. Rayner.
Cite this page: Hill, M.A. (2020, May 25) Embryology Paper - A model of the left half of the human mandible at the 17 mm CRL stage. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Paper_-_A_model_of_the_left_half_of_the_human_mandible_at_the_17_mm_CRL_stage
- © Dr Mark Hill 2020, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G