Carnegie stage 12

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Introduction

Stage12 sem1.jpg

Facts

Week 4, 26 - 30 days, 3 - 5 mm, Somite Number 21 - 29


Gestational Age GA week 6

Summary

  • Ectoderm: Neural tube continues to close, Caudal neuropore closes, forebrain
  • Mesoderm: continued segmentation of paraxial mesoderm (21 - 29 somite pairs), heart prominence
  • Head: 1st, 2nd and 3rd pharyngeal arch, forebrain, site of lens placode, site of otic placode, stomodeum
  • Body: heart, liver, umbilical, early upper limb bulge


See also Carnegie stage 12 Events

Features

  • Features: day 26, 27 somites, forebrain, site of lens placode, site of otic placode , stomodeum, 1st pharyngeal arch, 2nd pharyngeal arch, 3rdpharyngeal arch, heart prominence, somite
  • Identify: forebrain, site of lens placode, site of otic placode, stomodeum, first pharyngeal arch, second pharyngeal arch, third pharyngeal arch, heart prominence, somite


Stage 12 Links: Week 4 | Somitogenesis | Placodes | Head | Lecture - Early Vascular | Lecture - Gastrointestinal | Lecture - Head Development | Science Practical - Gastrointestinal | Science Practical - Head | Carnegie Embryos | Category:Carnegie Stage 12 | Next Stage 13
  Historic Papers: 1907 Somites 23 | 1914 | 1914 somites 27 | 1926 Somites 22 | 1926 Precervical Sinus | 1928 Somites 23 | 1937 Somites 25
Week: 1 2 3 4 5 6 7 8
Carnegie stage: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23
Carnegie Stages: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | About Stages | Timeline

Bright Field

Stage12 bf2.jpg Stage12 bf1.jpg Stage12 bf3.jpg

Stage12 bf4.jpg

Scanning EM

Image Source: Scanning electron micrographs of the Carnegie stages of the early human embryos are reproduced with the permission of Prof Kathy Sulik, from embryos collected by Dr. Vekemans and Tania Attié-Bitach. Images are for educational purposes only and cannot be reproduced electronically or in writing without permission.

Kyoto Collection

Stage12 bf5.jpg

View: Lateral view, day 26, 27 somites, Amniotic membrane removed.



Image source: The Kyoto Collection images are reproduced with the permission of Prof. Kohei Shiota and Prof. Shigehito Yamada, Anatomy and Developmental Biology, Kyoto University Graduate School of Medicine, Kyoto, Japan for educational purposes only and cannot be reproduced electronically or in writing without permission.

Carnegie Collection

Stage12 bf6.jpg Stage12 bf8.jpg

Stage12 bf7.jpgStage12 bf9.jpg Stage12 bf10.jpg

Carnegie Stages: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | About Stages | Timeline
Carnegie Collection - Stage 12 
Serial No. Pairs of somites Size (mm) Grade Fixative Embedding Medium Plane Thinness (µm) Stain Year Notes
209 ca_24 EH3 Ch.,15 Poor Alc P Coronal 50 Al. coch. 1902
250 19? E , 2 (11, 10x9x9 Poor p  ? Sagittal 20 Al. coch. p
384 P E 2_5 Ch.,13 Poor Formol P Transverse 10 H.&E. 1907 Macerated. Narrow yolk stalk
486 21 E.,4 Ch., 22 Good Corros. acetic P Transverse 10 Al. Coch. 1911
1062 29 E.,4.5 Ch., 20 Good Formol P Transverse 20 Al. coch. 1915 Transitional to next stage
2197  ? E_,5_3 Ch., 19.5 Poor Formol P Transverse 10 Al. coch, or. G. 1918
4245-7 ca.24 E.,3.5 Ch., 24 Good Alc, formol P Transverse 10 Al. coch. 1923 Caudal neuropore widely open
4479 P E.,5 .8 Ch , 17 Poor Formol P Transverse 40 Al. coch. 1923 Macerated. Upper lirnb buds not visible
4736 26 E.,3.0 Ch.,20 Good Formol P Coronal 10 Al. coch. 1924 No upper limb buds. Caudal neuropore closed
4759  ? E.,4.5 Ch.,15 Good Formol P Transverse 15 (Stain - Haematoxylin Eosin) 1924 Neural tube folded
4784 23 E_,3 Good P P Transverse 10 p 1924
5035 25-28 E.,3.8 Ch.,18 Good Formol C-P Transverse 10 Al. coch. 1925
5048 ca_25 E_,3_5 Good Formol C-P Transverse 10 Al. coch. 1925 Tubal Injured
5056 25 E,,3 Ch.,12 Good Formol P Transverse 10 Al. coch. 1925
5206  ? E.,4 Ch., 51x31x30 Poor  ?? P Transverse 20 Al. coch. 1926 Tubal
5300  ? E., 4.5 Ch,16.5 Poor Formol P Transverse 20 Al. coch. 1926 Autopsy. Partly macerated
5923 28 E.,4 Ch.,15 Exc. Formol P Transverse 10 Al. coch. 1929
6097 25 E,3.4 Ch., 12.5 Exc. Formol C-P Transverse 10 Al. coch, eosin 1930 Tubal Ag added to slides 1-3
6144 27 E. 3.3 Ch.,11 Good Lysol—Zenker C—P Transverse 10 Al. coch. 1930
6488 28 E, 32 Ch,22 Good Formol C—P Transverse 10 Al. coch. 1932
6937 26 E.,3 Ch , 12 Poor Formol C—P Coronal 10 I.H.,or.G. 1934 Tubal Caudal neuropore closed
7724 ca.29 E,3.5 Ch.,18 Good Formol C—P Sagittal 8 (Stain - Haematoxylin Eosin) 1940 Caudal end broken
7852 25 E , 3.7 Ch,26 Exc. Formol C—P Transverse 10 (Stain - Haematoxylin Eosin) 1940 Typical for stage 12
7999 ca.28 E,3.2 Ch , 15 Exc. Bruin C-P Transverse 10 (Stain - Haematoxylin Eosin) 1942 Caudal defect
8505a 24 Ch, 23.5 Exc. Formol C-P Transverse P H. Phlox. 1947
8505b 23 Ch,24 Exc. Formol C-P Sagittal p Azan 1947 Twins
8941 28 E,4.9 Ch, 35 Exc. Zenker C-P Transverse 6 I.H. 1927 Univ. Chicago No. H 1261
8942 25 E, 38 Ch, 35 Exc. Formal-Zenker C-P Coronal 5 11-1. 1930 Univ. Chicago No. H 1382
8943 22 E. 3.9 Ch, 20.4 Exc. Formal-Zenker C-P Transverse 8 H.&E. 1934 Univ. Chicago No. H 1481
8944 25 E,4 Ch,,25 Exc. Formal-Zenker C-P Sagittal 8 I.H. 1936 Univ. Chicago No. H 1514
8963 22 E, 3.8 Ch , 14.5 Fair Formol C-P Transverse 10 I.H. 1928 Univ. Chicago. No. H 1093 Studied by Wen (1928)[1]
8964 23 E,2.8 Ch - 25 Poor Formol p Transverse 8 I.H. 1928 Univ_ Chicago No. H984 Studied by Wen (1928)[1]
9154 24 E, 5 4 Exc Formal C-P Transverse I.H. & phlox. 1953
Abbreviations
  • Size - E. is the greatest length of the embryo and Ch. is the mean diameter of the chorion.
  • Grade - total grade of the specimen and includes both its original quality and the condition of the mounted sections.
  • Embedding medium - paraffin (P) or a combination of celloidin and paraffin (C-P).
  • Fixative - formalin (Formol), alcohol and formalin (Alc, formol), Bouin (Bouin solution)
  •  ? - unknown or not determined.
References
  1. 1.0 1.1 Wen IC. The anatomy of human embryos with seventeen to twenty-three pairs of somites (1928) J. Comp. Neural., 45: 301-376.


iBook - Carnegie Embryos  
link=http://itunes.apple.com/au/book/the-carnegie-staged-embryos/id510004473?mt=11 iTunes link
  • iTunes link | iBook Store
  • Description - Imagine the excitement of seeing this incredible early period of human development for the first time. Now consider that much of our initial understanding of human development is based upon study of historic embryo collections. You can now look at these historic images of the first 8 weeks after fertilisation and explore for yourself the changes that occur in human development during this key period. This current book is designed as an atlas of the Carnegie embryo stages with some brief notes and additional information covering the first 8 weeks of development. These images are from from the beginning of last century and are one of the earliest documented series of human embryos collected for basic research and medical education on development. I hope you enjoy learning about the amazing early events that begin to make and shape us. This is the second book in a series of educational releases from UNSW Embryology.
  • Release: First Edition - Mar 12, 2012 ISBN 978-0-7334-3148-7 Print Length 82 Pages, 25.8 MB Language English.
  • PDF Preview version 3.87 MB (Read the associated information, this is an edited educational preview version with many features not functioning).
  • The current website also includes numerous embryo images from this textbook (see Embryonic Development and Carnegie Embryos).

Hill Collection

HillH4 Stage 12 bf01.jpg HillH4 Stage 12 bf02.jpg
right view left view
Links: Hill Collection

Hinrichsen Collection

ME50 001.jpgME50 002.jpg

Hinrichsen collection Human Embryo ME50 (stage12).

Note the developing pharyngeal arches, otic and optic placodes, and heart in this left lateral view of the embryo.

Image source: The Hinrichsen Collection images are reproduced with the permission of Prof. Beate Brand-Saberi, Head, Department of Anatomy and Molecular Embryology, Ruhr-Universität Bochum. Images are for educational purposes only and cannot be reproduced electronically or in writing without permission.


Historic Embryology

Chicago Collection H1093 and H984

H1093 and H984 are University of Chicago Collection 22 and 23 somite embryos respectively, described by Wen, I. C., The anatomy of human embryos with seventeen to twenty-three pairs of somites J. Comp. Neural, 1928, 45:301-376.

Events

  • Somitogenesis - stages 12 and 13 embryo somite 1 has dispersed and is now contributing to the hypoglossal cord. Therefore “in embryos with more than 20 somites” (beginning of stage 12), the first ones visible “actually are second somites”.[1]
  • hearing - otic vesicle (otocyst) is forming and connects by a narrow pore with the surface[2] Otocyst ventral wall contributes to the vestibulocochlear crest.
  • Meninges (Spinal Cord) - a great advance has occurred in the migration of cells about the neural tube, as well as a further increase in the size of the neural crests (spinal ganglia). The ventrally migrating neural crest cells are still quite clearly distinct from the somites. This may indicate that the tissues immediately adjacent to the periphery of the neural tube originate from the neural crest. It is in this group that vascularization of the tissue surrounding the neural tube begins.[3]



References

  1. Arey, L. B. 1938. The history of the first somite in human embryos. Carnegie Instn. Wash. Publ. 496, Contrib. Embryoi, 27, 233-269.
  2. Streeter GL. Developmental horizons in human embryos. Description of age group XI, 13 to 20 somites, and age group XII, 21 to 29 somites. (1942) Contrib. Embryol., Carnegie Inst. Wash. Publ. 541, 30: 211-245.
  3. Sensenig EC. The early development of the meninges of the spinal cord in human embryos. (1951) Contrib. Embryol., Carnegie Inst. Wash. Publ. 611,


Wen, I. C., The anatomy of human embryos with seventeen to twenty-three pairs of somites J. Comp. Neural, 1928, 45:301-376.

Additional Images

Other Embryos

Sgalitzer KE. Contribution to the study of the morphogenesis of the thyroid gland. (1941) J Anat. 75(4): 389-405. PMID 17104869

  • Embryo Bs 26-27 pairs of somites
  • Embryo Fu 28 pairs of somites
  • Embryo F (4 mm 28 somites).

Historic Images

Historic Disclaimer - information about historic embryology pages 
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Pages where the terms "Historic Textbook" and "Historic Embryology" 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 and interpretations may not reflect our current scientific understanding.     (More? Embryology History | Historic Embryology Papers)


Historic Papers: 22 Somites | 23 Somites | 25 Somites | 27 Somites | Brain Vascular System of the Human Embryo


Glossary Links

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Cite this page: Hill, M.A. 2017 Embryology Carnegie stage 12. Retrieved November 24, 2017, from https://embryology.med.unsw.edu.au/embryology/index.php/Carnegie_stage_12

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© Dr Mark Hill 2017, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G