Paper - Description of a Human Embryo of 13-14 Mesodermic Somites

Alexander Low

University of Aberdeen

Anatomy Department, University of Aberdeen

Online version

This is a slightly edited version of the original 1908 paper published in J Anat Physiol. The full paper is still available as a PDF document through PubMed Central.

Historic Paper - Description of a Human Embryo of 13-14 Mesodermic Somites (1908) by Alexander Low

<pubmed>17232769</pubmed>| PMC1289161

THE human embryo Pfannenstiel- III. was placed at the disposal of Pro- fessor Keibel, for publication in his Normentafel zur Entwickelu4qgs- geschichtedes Menschen,by Professor Pfannenstiel of Griefswald. Inthe NormentafeltheembryoisNo.6(fig.Vr.andVv.) ProfessorKeibel kindly afforded me the opportunity of studying this embryo in the Anatomical Institute in Freiburg, and at his suggestion I undertook to reconstruct models of the embryo according toBorn's method. The work of modelling was begun in the Anatomical Institute in Freiburg, and completed in the Anatomy Department, Aberdeen University.

The embryo Pfannenstiel I. was obtained at an operation, and as measured through the amnion had a length of 2-6mm. The embryo was fixed in formalin-Muller's fluid, stained in paracarmine, and sectioned at a thickness of 10MA. Histologically the embryo is in an excellent state of preservation. A model of the whole embryo has been reconstructed at an enlargement of 100. A separate model of the nervous and alimentary systems has also been made, and three models of pharynx, heart with its blood-vessels, and septum transversum at an enlargement of 150.

External Form

(Plates I. and II.) The embryo is somewhat similar to the embryo von Bulle of Kollmann (7), which shows fourteen mesodermic somites and measured 25mm. in length, but is not so far developed; indeed, its outer form more nearly approaches that of the embryo of eight paired somites and a length of 2.15 mm. described and modelled by Professor Eternod (4). Like the Eternod embryo, it is spirally twisted in its long axis, and shows the same three back curvatures -a convex neck bend, a concave dorsal, and a convex rump. The dorsal flexure is slight, while the neck bend makes a right angle with the body, approaching in this respect the form of the embryo of twenty-three somites and a length of 2.15mm. described by Professor Peter Thompson(9). The medullary plate is still open at its head and caudal ends. The front of the head is directed down and slightly to the right over the bulging heart region,and thus is formed a well-developed stomodaeum. Three visceral clefts are visible-the first and second being deep, the third a shallow groove. The first and second visceral clefts lie dorsal to the rounded swelling caused by the commencing mandibular arch.

Explanation of Plates

Plate I

Model of the embryo, left side (enlarged 60 times).

Plate II

Model of the ernbiyo. frontil view (enlarged 60 times).

Plate III

The same model in sagittal section, viewed from the left.

Al., alanitoic duiet; Am., anmnion; Ao., origin of first aortic arch; B.S., body stalk ; Ch., chorda dorsalis ; (ltr., choriol ; Cl., cloaca; Cae., ewlom ; D.M., dorsal miesentery; F.B., fire-braii; F.G., fore-gut; G.af., ganglion acustico-facialis; H.G., biind-gut; Ily., hypophysis; AM., mouth ; M.B., midl-brain; Ml.G., mid-gut; Op.,01)ticvesicle; (it.,oticpit;P.C.,l)elicardialceloom;S.T'.,septutnitransversum $1., sinus venosus; T'h., mediant thyroid ; 1.(Ta., lefGuumbilical artery; 1.U.r.%, left umbilical vein; r.U.r. right umbilical vein; Y.S., yolk sac; I. ald III., firstand third visceral clefts; I.-YVIJ., first to seventh neuronieres.

Bibliography

(1) BORN, G., " Beitrige zur Entwicklungsgeschichte des Saugethierherzens," Arich.f/.nik/r. Anat., Bd. xi., 1889.

(2) BREMER, J. L., "Description of a 4 mnm. Human Embryo," The American JowanalofAnatomy, vol.v.,1906.

(3) BROMAN, J., " Beschreibung eines menschlichen Embryos von beinahe 3 mm. Lange, mit spezieller Bemerkung uber die bei demselben befindfichen Hirnfalten," Morph. Arbeiten, Bd. v., 1896.

(4) ETERNOD,A.,"Surun ceufhumainde1-3mm.avereimbryonde,21mm.," Actes de la Societe helcetique des Sciences naturelles, Zurich, 1896.

(5) His, WV., Anatomie menscilicher Embr-yonen, Leipzig, 1885.

(6) INGALLS, N. W., "Beschreibung eitiesmenschlicheniEmbryos von 4.9inm.," Archivf. mikr. Anat., Bd. lx., 1907.

(7) KOLLMANN, J., " Die Ktrperform menschlicher normaler und pathologiselmer Embryonen," Arch.f. Anat. u.Phys., Suplemi.Bd., 1889.

(8) MALL, F. P., "Onl the Development of the Human Diaphragm," Johns Hopkins Hospital Bulletin, vol. xi., 1901.

(9) THOMPSON, P.,"DescriptionofaHuman EmbryoofTwenty-threePaired Somites," Jour-n. of Anat. and Phys., xli., 1907.

(10) THOMPSON, P., " A Note on the Development of the Septum rransversum and the Liver," Joumn. of Anat. and Phy1s.,xli., 1908.

References

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Cite this page: Hill, M.A. (2024, June 1) Embryology Paper - Description of a Human Embryo of 13-14 Mesodermic Somites. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Paper_-_Description_of_a_Human_Embryo_of_13-14_Mesodermic_Somites

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