1987 Developmental Stages In Human Embryos - Stage 10
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O'Rahilly R. and Müller F. Developmental Stages in Human Embryos. Contrib. Embryol., Carnegie Inst. Wash. 637 (1987).
| Online Editor Note |
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| O'Rahilly R. and Müller F. Developmental Stages in Human Embryos. Contrib. Embryol., Carnegie Inst. Wash. 637 (1987).
The original 1987 publication text, figures and tables have been altered in formatting, addition of internal online links, and links to PubMed. Original Document - Copyright © 1987 Carnegie Institution of Washington.
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- 1987 Stages: Introduction | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | References | Appendix 1 | Appendix 2 | Historic Papers | Embryonic Development
| Historic Disclaimer - information about historic embryology pages |
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Stage 10
- Approximately 1.5–3 mm in length
- Approximately 22 ± 1 postovulatory days
- Characteristic feature: 4–12 pairs of somites
Summary
External: 4–12 pairs of somites; fusion of neural folds is imminent or in progress; the optic sulcus may have appeared; pharyngeal arch 1 begins to be visible on the surface.
Internal: the cardiac loop is appearing; the laryngeotracheal sulcus develops; the intermediate mesoderm becomes visible.
Size and Age
The chorion generally has a diameter of 8–15 mm. The greatest length of the embryo, although not of great informational value (Bartelmez and Evans, 1926), is usually 1.5–3 mm.
The age is approximately 22 postovulatory days. A brief review of stage 10 was published by Heuser and Corner (1957), and a detailed investigation of this stage was undertaken by Müller and O'Rahilly (1985), who provided graphic reconstructions. Both of these publications contain an appropriate bibliography.
External Form
(figs. 10-1 and 10-2) The criterion for stage 10 is the presence of 4–12 pairs of somites. This stage is particularly important because, during it,the neural tube first begins to be formed from the neural folds and groove. In the less advanced specimens the neural groove is open throughout its whole length, whereas by the end of the stage the groove is closed from the rhombencephalon to below the level of the last somites present.
The embryo is becoming longer, and the umbilical vesicle continues to expand. The rostral portion of the neural folds becomes elevated, a caudal fold begins to appear, and the whole embryo comes to rise beyond the level of the umbilical vesicle (i.e., a variable degree of lordosis usually becomes evident). By the end of the stage the cardiac region has become a prominent feature of the external form (Boyden, 1940).
Representative specimens of this stage are illustrated in figures 10-3 and 10-4. These outlines, showing the dorsal aspect of a median section of each specimen, are enlarged to the same scale. As pointed out by Bartelmez and Evans (1926), the mesencephalic flexure is present in all embryos of this period. A dorsal flexure may or may not be found. The curvature of the dorsal profile varies from a gentle convexity through all degrees of concavity (lordosis) from the least possible curve to a deep, sharp kink. Bartelmez and Evans (1926) and Streeter (1942) have discussed the significance of this variation as seen in human and rhesus embryos of early somitic stages. On the whole, the evidence indicates that, whereas extreme dorsal flexion should be regarded as an artifact, anything from a gentle convexity to a moderate dorsal concavity can be considered normal.
The optic sulcus develops in the forebrain and, toward the end of the stage, an indication of invagination of the otic disc is found. During stage 10, swellings begin to appear for the mandibular arch (Politzer, 1930, fig. 5), and the hyoid arch and probably the maxillary process become identifiable (Bartelmez and Evans, 1926, fig. 6). Pharyngeal cleft 1 becomes visible (Corner, 1929, figs. 4 and 10).The future ectodermal ring (O'Rahilly and Müller, 1985) is beginning to form as a thick area overlying pharyngeal arch 1. An indication of an intermediate band is present and represents the future intermembral part of the ectodermal ring.
Specimens of Stage 10 Already Described
- 4 somites, Carnegie No. 3709 (University of Chicago H 279). Characterized with outline sketches, by Bartelmez and Evans (1926).
- 4 somites, Histologisch-Embryologisches Institut, Embryo A, Vienna. Fully described by Sternberg (1927).
- 4 somites, Histologisch-Embryologisches Institut, Embryo Ca, Vienna. Fully described by Orts Llorca (1934).
- 4–5 somites, Florian's Embryo Bi II. The whereabouts of this, the following embryo, and the 10-somite Bi XI (see below) are not known; Florian's collection has not been found since his untimely death during World War II. The embryo Bi II was briefly characterized by Studnicka (1929), cited and partly illustrated by Florian (1928, 1930a).
- 4–5 somites, Florian's Embryo Bi III. (See note on previous embryo.) Briefly characterized by Studnicka (1929) and cited by Florian (1928).
- 4–5 somites, Carnegie No. 2795. Cited and briefly characterized by Bartelmez and Evans (1926). The specimen is distorted and somewhat macerated.
- 5 somites, Anatomisches Institut, Zürich, GM 1954. Described and illustrated by Schenck (1954).
- 5 somites, No. 103, Department of Anatomy, Tohoku University, Sendai. Distribution of alkaline phosphatase studied by Mori (1959a) in this and in another (No. 101), possibly 8-somite, embryo.
- 5–6 somites, Pfannenstiel “Klb” (originally at Giessen; was in Keibel's Institute at Freiburg i. Br. about 1911, may now be in Berlin). This well known embryo is No. 3 in the Keibel and Elze Normentafel (1908). Models by Kroemer (1903). A partial set of tracings made by H. M. Evans is in the Carnegie Collection, No. 5463.
- 6 somites, Carnegie No. 8244. Somewhat distorted; histologically fair.
- 6 somites, University of Michigan No. 71, Ann Arbor. Briefly described by Arey and Henderson (1943). A full description in an unpublished doctoral dissertation is in the files of L. B. Arey at Northwestern University, Chicago.
- 6 somites, Carnegie No 8818 (University of Chicago H 338) Pathological, not used in present study. Listed here because cited by Bartelmez and Evans (1926).
- 6–7 somites. His’s Embryo “SR.” Cited by His (1880) and by Bartelmez and Evans (1926). Has been studied only in the gross.
- 6–7 somites, Embryo LM (present location unknown). Cited here from manuscript notes at Carnegie laboratory, made from Russian text of Burow (1928). Condition said to be poor.
- 7 (?) somites, Embryo “Ludwig,” Berlin. Described by Streiter (1951). This specimen, which is somewhat macerated, is in certain characteristics considerably in advance of others of similar somitic number.
- 7 somites, Carnegie No. 6330 (University of Chicago H 1404). Extensive manuscript notes on this specimen, made under the supervision of G. W. Bartelmez, are in the files of the Carnegie laboratory.
- 8 somites, Carnegie No. 4216. Described by Payne (1925), and very frequently cited.
- 8 somites, Dublin. Described by West (1930); see also Arey (1938). Photographs and models are in the Carnegie Collection, No. 4923. Bartelmez (personal communication) thinks that this distorted embryo had only 5–6 somites.
- 8 somites, Carnegie No. 391. Described by Dandy (1910) and frequently cited (cf. Bartelmez and Evans, 1926, with additional illustrations). There were neither camera drawings nor photographs of the intact specimen, and therefore the reconstructions are not entirely satisfactory. The plaster models now at the Carnegie laboratory were made by O. O. Heard under the supervision of Bartelmez for the paper by Bartelmez and Evans (1926). The apparent lack of fusion of the neural folds described by Dandy is an artifact produced by a crack.
- 8 somites, Carnegie No. 1201 (University of Chicago H 87). Described briefly by Evans and Bartelmez (1917); cited, with illustrations, by Bartelmez and Evans (1926).
- 8 somites, Embryologisches Institut, Embryo Ct, Vienna. Fully described by Politzer (1930). Arey (1938) counts 8 paired somites in this embryo instead of 7 as stated by Politzer.
- 8 somites, University of Cambridge, Department of Anatomy H 98. Photographs and models in Carnegie Collection, No. 7251. Described by J. T. Wilson (1914). Cited by Bartelmez and Evans (1926), who consider it slightly abnormal in form although good histologically.
- 9 somites, Embryo “Esch I,” Marburg. Elaborately described by Veit and Esch (1922), and cited, with illustrations, by Bartelmez and Evans (1926), who count 9 somites instead of 8 as stated by the original authors. Chorionic villi studied in detail by Ortmann (1938). Photographs and models are in the Carnegie Collection, No. 4251.
- 9 somites, Embryo “Du Ga,” Geneva. Described by Eternod (1896); models by Ziegler were distributed commercially. Cited by Bartelmez (1922) and Bartelmez and Evans (1926), with illustrations. Tracings made by H. M. Evans at Geneva and models are in the Carnegie Collection, No. 4439.
- About 9 somites. Embryo Unger, Keibel Collection, Freiburg i. Br., No. 4 of Keibel and Elze (1908). Listed by Bartelmez and Evans (1926).
- 9 somites, Embryo “Jacobsen,” formerly at Kiel (Graf Spee's collection was destroyed in World War II). Described by von Spee (1887). Listed by Bartelmez and Evans (1926) as having “at least” 9 somites.
- 9 somites, Embryo Ca of Orts Llorca, Madrid. Various details described by Mari Martinez (1950) and Martinez Rovira (1953).
- 9–10 somites, Embryo R. Meyer 335. (Robert Meyer's collection was purchased by the late Hedwig Frey and bequeathed by him to the Anatomisches Institut, University of Zurich.) Listed by Bartelmez and Evans (1926), and cited by Felix (1912).
- 10 somites, Da2, Anatomical Institute, Basel. Described by Ludwig (1929). Plastic reconstructions. Neural groove closure extends rostral to otic discs.
- 10 somites, Carnegie No. 5074 (University of Rochester H 10). Fully described by Corner (1929), and subjected to volumetric analysis by Boyden (1940). Excellent specimen.
- 10 somites, Grosser's Embryo Schwz (present location unknown). Briefly described, without illustrations, by Treutler (1931). Preservation said to be not altogether satisfactory.
- 10 somites, Florian’s Embryo Bi XI. (See note on Bi II above.) Briefly described, with illustrations, by Politzer and Sternberg (1930); cited and partly illustrated by Florian (1930a).
- 10 somites, Anatomy Department, University of South Wales, Cardiff. Partly described and illustrated by Baxter and Boyd (1939).
- 11 somites, Embryo T 152, University of Toronto, Department of Anatomy. Cited by Arey (1938).
- 11 somites, Embryo G-dt, Uppsala. Described by Holmdahl (1943) as having 11 well-differentiated pairs of somites, with beginning delimitation of 4 more.
- 11–12 somites, Carnegie No. 8970 (University of Chicago H 637). Somewhat damaged. Cited, with illustrations, by Bartelmez (1922) and Bartelmez and Evans (1926).
- 12 somites, Carnegie No. 3710 (University of Chicago H 392). Cited by Bartelmez (1922) and Bartelmez and Evans (1926).
- 12 somites, Carnegie No. 3707 (University of California H 197). “Legge embryo.” Cited, with illustrations, by Bartelmez and Evans (1926). The coital history accompanying this specimen, which was declared to be reliable, would give it a postovulatory age of either 18 or 39 days; the former seems rather brief but the latter is much too long.
- 12 somites, Litzenberg embryo, University of Minnesota, Minneapolis. Briefly described by J. C. Litzenberg (1933); characterized and subjected to volumetric analysis by Boyden (1940), who counts 12 somites instead of 13–14 as in the original description. Photographs and model in Carnegie Collection, No. 6740.
- 12 somites, M. 24, University of Michigan, Ann Arbor. Cited by Arey (1938).
References
| Online Editor Note |
|---|
| O'Rahilly R. and Müller F. Developmental Stages in Human Embryos. Contrib. Embryol., Carnegie Inst. Wash. 637 (1987).
The original 1987 publication text, figures and tables have been altered in formatting, addition of internal online links, and links to PubMed. Original Document - Copyright © 1987 Carnegie Institution of Washington.
|
Search Pubmed
- 1987 Stages: Introduction | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | References | Appendix 1 | Appendix 2 | Historic Papers | Embryonic Development
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Cite this page: Hill, M.A. (2024, April 24) Embryology 1987 Developmental Stages In Human Embryos - Stage 10. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/1987_Developmental_Stages_In_Human_Embryos_-_Stage_10
- © Dr Mark Hill 2024, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G
