File:Frazer1926 fig05.jpg

From Embryology

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Fig. 5. Head of Embryo (12 mm)

Left side of region in an embryo of 12 mm showing the structures behind the mouth, m. I, II, III, pharyngeal arches; P, pericardium.

Ectodermal connections with placodal cysts indicated at pl. IX, pl. X.

Fig. 5 gives the surface view of the region in an embryo barely 12mm. in length. In this specimen the two placodal areas form buried cysts (cervical vesicles)related to the corresponding ganglia. Cyst X is connected with the surface still by a definite epithelial strand, enclosing a lumen at its inner end, but otherwise apparently a solid thin cord: placodal cyst IX has lost its connection with the surface, but the line formerly taken by this can, I think, be made out. The duct of this cyst disappears apparently about the 11 mm. stage. The position of these two points of final attachment to the ectoderm in the 12mm. embryo can be seen in the figure:the third arch lies, as before, between them, bounded behind by a very shallow but definite groove, and the condition is as in the 10mm. embryo with the exception that the two open ducts have been closed.

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Pages where the terms "Historic" (textbooks, papers, people, recommendations) appear on this site, and sections within pages where this disclaimer appears, indicate that the content and scientific understanding are specific to the time of publication. This means that while some scientific descriptions are still accurate, the terminology and interpretation of the developmental mechanisms reflect the understanding at the time of original publication and those of the preceding periods, these terms, interpretations and recommendations may not reflect our current scientific understanding.     (More? Embryology History | Historic Embryology Papers)
Links: Fig. 1. Embryo 4-9 mm | Fig. 2. Semi-schematic pharyngeal region | Fig. 3. Embryo 8 mm | Fig.4. Embryo 10 mm | Fig. 5. Embryo 12 mm | Fig. 6. Embryo 10 mm | Fig. 7. Third Arch | Fig. 8. Laranryngeal Area of Head | Plate 1. Fig.1,3,4


Frazer JE. The disappearance of the precervical sinus. (1926) J Anat. 61(1): 132-43. PMID 17104123.

Cite this page: Hill, M.A. (2024, May 28) Embryology Frazer1926 fig05.jpg. Retrieved from

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

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current11:19, 28 July 2015Thumbnail for version as of 11:19, 28 July 20151,000 × 643 (85 KB)Z8600021 (talk | contribs)
11:17, 28 July 2015Thumbnail for version as of 11:17, 28 July 20151,432 × 812 (141 KB)Z8600021 (talk | contribs)==Fig. 5. == {{Frazer1926 figures}}

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