File:Streeter1922-fig50.jpg

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Fig. 50. Embryo No. 2274, 113 mm CRL

Figure 49 shows a marked development of the transverse folds in the region of the anthelix, which were first described by Schwalbe and interpreted by him as temporary representatives of the longitudinal folds seen in some of the long-eared mammals. The fact that they are so irregular in occurrence, however, as can be seen by this and the next plate, makes it doubtful whether these folds can be safely interpreted as phylogenetic rudiments. I am inclined rather to attribute them to a redundancy of the soft tissues of the anthelix. This specimen illustrates very well the difference in character between the auricular derivatives of the mandibular bar (cms helicis and tragus) and the derivatives of the hyoid bar (scapha-helix, anthelix, antitragus, and lobule). In the last specimen on this plate (fig. 50), in contrast with figure 49, there are no distinct transverse folds, but the plica principalis is more prominent.


Plate 5. Photographs showing changes occurring in the auricle of the human fetus during the fourth month

The photographs shown on plate 5 represent the changes occurring in the auricle during the fourth month of intrauterine life. As compared with the photographs on plate 4, the principal change is a relative decrease in the size of the crus helicis and tragus. Corresponding to this, it is possible to recognize a conchal cavity which has heretofore been nothing more than a cleft. The concha in the first two photographs (figures 42 and 43) appears to me a little exaggerated, due, probably, to the shrinkage of the auricle. Judging from the preceding and succeeding photographs, the average auricle at this time would be somewhat plumper in appearance. Owing to the fact that these are thinner, one can see for the first time the presence of the plica principalis.


Specimens are from the Carnegie Collection, and length given is crown-rump.


In-text Figures: Figure 1 and 2 | Figure 3 and 4 | Figure 5 | Figure 6 and 7 | Figure 8 | Text | Glossary
Plates: Plate 1 | Plate 2 | Plate 3 | Plate 4 | Plate 5 | Plate 6 | Plates | Glossary
Figures: 1. Auricle cartilage | 2. External ear | 3. Agnathia | 4. Agnathia+cyclopia | 6. Auricular cartilage embryo 21, 32 and 43 mm | 7. Auricular cartilage 50 mm fetus | 9. Embryo 6 mm | 10. Embryo 12 mm | 11. Embryo 14 mm | 12. Embryo 18 mm | 13. Embryo 1380, 5 mm | 14. Embryo 1767, 11 mm | 15. Embryo 1461, 10 mm | 16. Embryo 562, 13 mm | 17. Embryo 1232, 14 mm | 18. Embryo 475, 15 mm | 19. Embryo 899, 13 mm | 20. Embryo 434, 15 mm | 21. Embryo 492, 16.8 mm | 22. Embryo 576, 17 mm | 23. Embryo 547, 18 mm | 24. Embryo 955, 17 mm | 25. Embryo 1584, 18 mm | 26. Embryo 1134e, 21.3 mm | 27. Embryo 1358b, 33.2 mm | 28. Embryo 1535, 28 mm | 29. Embryo 2163, 36 mm | 30. Embryo 1980, 37 mm | 31. Embryo 1840a, 38.5 mm | 32. Embryo 2075, 40 mm | 33. Embryo 2144, 45.5 mm | 34. Embryo 642, 49 mm | 35. Embryo 2170, 50 mm | 36. Embryo 2095, 52 mm | 37. Embryo 2095, 52 mm | 38. Embryo 2066, 53 mm | 39. Embryo 2079, 56.5 mm. | 40. Embryo 1561, 57 mm | 41. Embryo 218, 62.5 mm. (R.) | 42. Embryo 1724, 66.2 mm | 43. Embryo 2328, 65 mm | 44. Embryo 2118, 69 mm | 45. Embryo 981, 85 mm | 46. Embryo 1845, 87 mm | 47. Embryo 1449, 87.3 mm | 48. Embryo 2003, 103.5 mm | 49. Embryo 1858, 100 mm | 50. Embryo 2274, 113 mm | 51. Embryo 2185, 113.5 mm. | 52. Embryo 9526, 114 mm. | 53. Embryo 1811, 114 mm | 54. Embryo 1716, 119 mm. Fig. 59. 1742, 191.2 mm | 55. Embryo 19576, 119 mm. | 56. Embryo 1782, 135.6 mm | 57. Embryo 1702, 150 mm | 58. Embryo 1708, 154 mm | 59. Embryo 1742, 191.2 mm | Figures


Related Notes: Outer Ear Development | Carnegie Contributions to Embryology

Reference

Streeter GL. Development of the auricle in the human embryo. (1922) Carnegie Instn. Wash. Publ. 277, Contrib. Embryol., 14: 111-138.



Cite this page: Hill, M.A. (2024, April 13) Embryology Streeter1922-fig50.jpg. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/File:Streeter1922-fig50.jpg

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current08:08, 28 January 2013Thumbnail for version as of 08:08, 28 January 2013582 × 781 (97 KB)Z8600021 (talk | contribs)==Plate 5. Photographs showing changes occurring in the auricle of the human fetus during the fourth month== The photographs shown on plate 5 represent the changes occurring in the auricle during the fourth month of intrauterine life. As compared with th