Carnegie stage 12

Embryology - 1 Dec 2023 Expand to Translate
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Introduction

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

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
Caudal neuropore closes during this stage.

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

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

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

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 Embryos - 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	Formalin	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	Formalin	P	Transverse	20	Al. coch.	1915	Transitional to next stage
2197	?	E_,5_3 Ch., 19.5	Poor	Formalin	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	Formalin	P	Transverse	40	Al. coch.	1923	Macerated. Upper lirnb buds not visible
4736	26	E.,3.0 Ch.,20	Good	Formalin	P	Coronal	10	Al. coch.	1924	No upper limb buds. Caudal neuropore closed
4759	?	E.,4.5 Ch.,15	Good	Formalin	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	Formalin	C-P	Transverse	10	Al. coch.	1925
5048	ca_25	E_,3_5	Good	Formalin	C-P	Transverse	10	Al. coch.	1925	Tubal Injured
5056	25	E,,3 Ch.,12	Good	Formalin	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	Formalin	P	Transverse	20	Al. coch.	1926	Autopsy. Partly macerated
5923	28	E.,4 Ch.,15	Exc.	Formalin	P	Transverse	10	Al. coch.	1929
6097	25	E,3.4 Ch., 12.5	Exc.	Formalin	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	Formalin	C—P	Transverse	10	Al. coch.	1932
6937	26	E.,3 Ch , 12	Poor	Formalin	C—P	Coronal	10	I.H.,or.G.	1934	Tubal Caudal neuropore closed
7724	ca.29	E,3.5 Ch.,18	Good	Formalin	C—P	Sagittal	8	(Stain - Haematoxylin Eosin)	1940	Caudal end broken
7852	25	E , 3.7 Ch,26	Exc.	Formalin	C—P	Transverse	10	(Stain - Haematoxylin Eosin)	1940	Typical for stage 12
7999	ca.28	E,3.2 Ch , 15	Exc.	Bouin	C-P	Transverse	10	(Stain - Haematoxylin Eosin)	1942	Caudal defect
8505a	24	Ch, 23.5	Exc.	Formalin	C-P	Transverse	P	H. Phlox.	1947
8505b	23	Ch,24	Exc.	Formalin	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	Formalin	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	Formalin	p	Transverse	8	I.H.	1928	Univ_ Chicago No. H984 Studied by Wen (1928)^[1]
9154	24	E, 5 4	Exc	Formalin	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 ↑ ^1.0 ^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
	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


right view	left view

Links: Hill Collection

Hinrichsen Collection

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 (1928)^[1] - The anatomy of human embryos with seventeen to twenty-three pairs of somites..

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”.^[2]
neural - caudal neuroprkoe closes.^[3]
hearing - otic vesicle (otocyst) is forming and connects by a narrow pore with the surface^[4] 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.^[5]
genital - primordial germ cells are located within the wall of the hindgut.^[6]

References

↑ Wen IC. The anatomy of human embryos with seventeen to twenty-three pairs of somites (1928) J. Comp. Neural., 45: 301-376.
↑ Arey LB. The history of the first somite in human embryos. (1938) Contrib. Embryol., Carnegie Inst. Wash. Publ. 496, 27: 233-269.
↑ Müller F. and O'Rahilly R. The development of the human brain, the closure of the caudal neuropore, and the beginning of secondary neurulation at stage 12. (1987) Anat Embryol (Berl). 176(4): 413-430. PMID 3688450
↑ 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.
↑ Sensenig EC. The early development of the meninges of the spinal cord in human embryos. (1951) Contrib. Embryol., Carnegie Inst. Wash. Publ. 611.
↑ Witschi E. Migration of the germ cells of human embryos from the yolk sac to the primitive gonadal folds. (1948) Carnegie Instn. Wash. Publ. 575, Contrib. Embryol., 32: 67-80.

Thompson P. Description of a human embryo of twenty-three paired somites. (1907) J Anat Physiol, 41(3):159-71. PMID 17232726

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

Additional Images

Stage 12 Optical Projection Tomography

Historic Images

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