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Fig. 4. Pharynx

In Text-fig.4 I show a drawing of this region in the present specimen, together with tracings of the same area in the embryos described by Corner (1929), Heuser (1930), Low (1908), Davis (1923), Thompson (1907, 1908), Girgis (1926), Johnson (1917), and Waterston (1914).


In the earlier stages (Corner and Heuser) lung and liver are very close to each other; in Low's specimen I have marked a doubtful swelling which I believe represents the lung bud,but from his statements I do not think that this is the groove which Low considers (p. 245) "may indicate the lung groove", but that he would place it some distance further cranialwards.


In Davis' specimen liver and lung still are in close apposition, but in the embryo described by Thompson there is a sudden increase in the distance between the two rudiments, but what Thompson interprets as stomach Grosser (1912) would call lung bud, and Davis after a study of his own specimen naturally takes the same view as Grosser;


Girgis, in a 22-somite embryo, and van den Broek, in one of 28 somites, show the lung and liver rudiments so close to each other that parts of both are cut in the same section, a fact which is in keeping with Grosser's interpretation of Thompson's specimen;


in Johnson's specimen, of 24 somites and in the present one, of 25 somites, there is a much larger interval between lung and liver, and I agree with the interpretation of Johnson, as far as these two rudiments are concerned, though I am not so certain about his ?5th pharyngeal pouch;


in Waterston's embryo, of 27 somites, there is again a wide interval between lung and liver, and he shows a lung bud which can surely be interpreted as nothing but lung. In the earlier stages to which I have referred the lung bud is shown as being bifid at its caudal end, but such a bifid condition is not present in the more caudal swelling of Thompson's embryo, whereas it is present in the cranial swelling which Thompson calls lung bud. Furthermore, if Grosser is correct in his interpretation of the more caudal swelling as lung bud, itwould mean that this structure would come to an end right up against the dorsal surface of the liver bud, behind which it is hidden. The resemblance between Thompson's specimen and my own is so close that I find it difficult to believe that Grosser's interpretation is correct.

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Reference

West CM. A human embryo of twenty-five somites. (1937) J. Anat., 71(2): 169-200.1. PMID 17104635



Cite this page: Hill, M.A. (2024, March 28) Embryology West04.jpg. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/File:West04.jpg

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Historic Paper Links: 13-14 Somites | 22 Somites | 23 Somites | 25 Somites | 27 Somites | Mall Human Embryo Collection | Embryology History | Carnegie stage 11 | Carnegie stage 12 | Journal of Anatomy | Embryonic Development | Category:Historic Embryology


Reference

<pubmed>17104635</pubmed>| PMC1252340

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current16:21, 28 January 2012Thumbnail for version as of 16:21, 28 January 2012946 × 631 (61 KB)S8600021 (talk | contribs)==Fig. 4 == {{Template:West1937}} {{Historic Disclaimer}} {{Historic Papers}} ===Reference=== <pubmed>17104635</pubmed>| [http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1252340 PMC1252340] Category:Carnegie Stage 12

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