Carnegie stage 21

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Introduction

Stage21 bf1c.jpg

Facts

Week 8, 53 - 54 days, 22 - 24 mm

Gestational age GA week 10

Summary

  • Ectoderm: sensory placodes, nasal pits moved ventrally, fourth ventricle of brain
  • Mesoderm: heart prominence, ossification continues
  • Head: nose, eye, external acoustic meatus
  • Body: straightening of trunk, heart, liver, umbilical cord
  • Limb: upper limbs longer and bent at elbow, foot plate with digital rays begin to separate, wrist, hand plate with webbed digits


See also Carnegie stage 21 Events

Features

  • scalp vascular plexus, eylid, eye, nose, auricle of external ear, arm, elbow, wrist, knee, notch between digital rays, umbilical cord
  • Identify: straightening of trunk, pigmented eye, eyelid, nose, external acoustic meatus, scalp vascular plexus, webbed digits, liver prominance, thigh, ankle, foot plate, umbilical cord


Stage 21 Links: Week 8 | System Development | Lecture - Limb | Lecture - Head Development | Lecture - Sensory | Science Practical - Head | Science Practical - Sensory | Science Practical - Urogenital | Historic - Skull Development | Carnegie Embryos | Madrid Embryos | Category:Carnegie Stage 21 | Next Stage 22
  Historic Papers: 1897 Coelom | 1911 Larynx | 1954 Stage 19-23


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

Stage21 bf11a.jpg

Virtual Embryo Slides

Stage 21 - Left Lateral

Stage21 bf11.jpg

 ‎‎Mobile | Desktop | Original

Stage 21 | Embryo Slides

Kyoto Collection

Stage21 bf1a.jpg

View: This is a dorsolateral view of embryo. Amniotic membrane removed.

Central Nervous System
Human Stage21 neural01.jpg Human Stage21 neural02.jpg
left lateral view medial view
scale bar = 1mm
Kyoto940 stage21-01.jpg Kyoto940 stage21-02.jpg
Kyoto940 stage21-03.jpg


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

Stage21 bf2.jpg Stage21 bf3.jpg Stage21 bf4.jpg Stage21 bf5.jpg Stage21 bf6.jpg Stage21 bf7.jpg Stage21 bf8.jpg Stage21 bf9.jpg Stage21 bf10.jpg

Carnegie stage 21: 7592 Right | 7592 Anterior | 7592 Left | 8553 Right | 8553 Anterior | 8553 Left | 4090 Right | 4090 Anterior | 4090 Left


Carnegie Collection - Stage 21 
Serial No. Size (mm) Grade Fixative Embedding Medium Plane Thinness (µm) Stain Point Score Sex Year Notes
22 E, 20 Ch, 35x30x30 Good Alc. P Transverse 50 Al. coch. 34.5 Female 1895
57 E, 23 Ch., ca. 30 Poor Alc. P Sagittal 50 Al. coch. 36 Male 1896
128 E, 20 Ch., 50x43 Good Formol P Coronal 50 Al. coch. 33 Female 1898
229 E, 19 Poor Alc. P Sagittal 50 Al. coch. 33 Female 1903
349 E, 24 Good Zenker C Coronal 250 Unstained 36  ? 1905 Double vascular injection
455 E, 24 Ch., 42x34x20 Good Alc. P Transverse 30 (Stain - Haematoxylin Eosin) 36.5 Male 1910
632 E, 24 Ch., 60x50x30 Good Bichlor. acetic P Sagittal 40, 100, 250 Al. coch. 33 Female 1913 Injected
903C E, 23.5 Good Formol P Transverse 40 Al. coch. 38.5 Female 1914
1008 E, 26,4 Good Formol P Sagittal 40 Al. coch. 39  ?? 1914
1358F E, 23 Good Formol P Sagittal 40 Al. coch. 37.5 Female 1916
2937 E,, 24.2 Good Bouin P Transverse 50 (Stain - Haematoxylin Eosin) aur., or. G. 39 Female 1920
3167 E., 24.5 Ch., 60x50x40 Poor Bichlor, acetic, formol P Transverse 20 Al. coch. 32 Male 1920
4090 E, 22.2 Ch.. 66x46x30 Good Formol P Transverse 40 Al. coch. 30 Female 1922
4160 E,25 Poor Formol P Sagittal 25 (Stain - Haematoxylin Eosin) 39 Male 1923 Tubal
4960 E.22 Ch,, 47x42x28 Good Formol P Transverse 15 Al. coch., Mallory 31.5 Female 1925
5??6 E. 215 Good Formol P Sagittal 20 (Stain - Haematoxylin Eosin) 34 Female 1927
6531 E,22 Poor Glacial acetic, C-P Transverse 10 (Stain - Haematoxylin Eosin) 31.5 Female 1931 Leitz Collection
7254 E,225 Exc Bouin C-P Transverse 20 (Stain - Haematoxylin Eosin) 33.5 Male 1936
7592 E,22-> Exc. Bouin C-P Transverse 20 (Stain - Haematoxylin Eosin) 36 Female 1937
7864 E., 24 Exc, Formol C-P Frontal 20 (Stain - Haematoxylin Eosin) 32.5 Male 1941
8553 E., 22 Exc Bouin C-P Transverse 12 (Stain - Haematoxylin Eosin) 38 Female 1947
9614 E,,22 5 Exc Bouin P Coronal 10 &15 Azan  ?  ? 1958 Rubella. Hysterectomy
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)
  • Stain -
  •  ? - unknown or not determined.


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).

Hinrichsen Collection

frontal section respiratory excerpt
ME54 001.jpg ME54 002.jpg
ME54 003.jpg
Links: frontal section | respiratory excerpt | labeled respiratory excerpt | Carnegie stage 21 | Week 8 | Hinrichsen Collection

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.

Madrid Collection

Madrid Collection Embryos  
Carnegie
Stage
Embryo Days CRL (mm) Section
thickness
Staining Section plane
21 GV 7 51 22 10 (Stain - Haematoxylin Eosin) sagittal


Events

  • Hearing - tip of the cochlea is recurved.
  • Vision - (stage 19 -22) the eyelid folds develop into the eyelids and cover more of the eye as the palpebral fissure takes shape. The upper and the lower eyelids meet at the outer canthus in Stage 19.[2]
  • Musculoskeletal
    • Mandible bone-formation has taken place and formed a plate on the lateral side of Meckel's cartilage; this plate is in the substance of, and is surrounded by, that mesodermal condensation which outlines the mandible and precedes the formation of bone. The plate of bone is confined to the region of what approximately corresponds to the future body of the mandible, but the mesodermal condensation can be traced further backwards, always, of course, on the lateral side of Meckel's cartilage and the associated branches of the mandibular nerve. The condensation admittedly becomes gradually much less sharply defined but is still distinguishable from the surrounding tissue. Finally, some distance beyond the limit of bone-formation, the lateral pterygoid muscle can be seen running into and out- lining the terminal part of the mesodermal condensation. This is the first indication of the condylar process in my series (P1. 1, fig. 1). Meckel's cartilage with the inferior dental and lingual nerves on its upper surface lies medial to this rudimentary condylar area and inferior to the lateral pterygoid muscle.[3]
  • Joint - knee posterior cruciate ligament present.[4]
  • Cardiovascular
  • Endocrine System Development[6]
    • Hypophysis - the pharyngeal stalk becomes fragmented (Jirfisek 1980).
    • Adrenal Cortex - the cellular "capsule" becomes covered by a layer of fibrous tissue.[7]
  • Meninges (Spinal Cord) - cavity formation in the meninx primitiva has progressed, and the rudimentary ventral dura is more distinct. Ventral to the medial edge of the ganglia, this dense dural rudiment is separated from the lateral extremities of the centra and intervertebral disks. Within this space a large longitudinal venous channel is developing. The dura can be identified around the spinal ganglia, which are now shifting into the intervertebral foramina, but becomes less distinct as it passes dorsad. The ventral dura can be followed throughout the cervical, thoracic, and lumbar segments, but in the sacral segments it can be identified only on the dorsal surfaces of the intervertebral disks.[8]



References

  1. Streeter GL. Developmental Horizons In Human Embryos Description Or Age Groups XIX, XX, XXI, XXII, And XXIII, Being The Fifth Issue Of A Survey Of The Carnegie Collection. (1957) Carnegie Instn. Wash. Publ. 611, Contrib. Embryol., 36: 167-196.
  2. Pearson AA. The development of the eyelids. Part I. External features. (1980) J. Anat.: 130(1): 33-42. PMID 7364662 PDF
  3. N B B SYMONS The development of the human mandibular joint. J. Anat.: 1952, 86(3);326-32 PubMed 12980883 | PMC1273756
  4. J A Mérida-Velasco, I Sánchez-Montesinos, J Espín-Ferra, J R Mérida-Velasco, J F Rodríguez-Vázquez, J Jiménez-Collado Development of the human knee joint ligaments. Anat. Rec.: 1997, 248(2);259-68 PubMed 9185992
  5. Khaled Menshawi, Jay P Mohr, Jose Gutierrez A Functional Perspective on the Embryology and Anatomy of the Cerebral Blood Supply. J Stroke: 2015, 17(2);144-58 PubMed 26060802 | J Stroke.
  6. O'Rahilly R. The timing and sequence of events in the development of the human endocrine system during the embryonic period proper. (1983) Anat. Embryol., 166: 439-451. PMID 6869855
  7. Crowder RE. The development of the adrenal gland in man, with special reference to origin and ultimate location of cell types and evidence in favor of the "cell migration" theory. (1957) Contrib. Embryol., Carnegie Inst. Wash. 36, 193-210.
  8. Sensenig EC. The early development of the meninges of the spinal cord in human embryos. (1951) Contrib. Embryol., Carnegie Inst. Wash. Publ. 611,

Additional Images

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)


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Cite this page: Hill, M.A. 2017 Embryology Carnegie stage 21. Retrieved October 21, 2017, from https://embryology.med.unsw.edu.au/embryology/index.php/Carnegie_stage_21

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