Carnegie stage 18

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Introduction

Stage18 bf1c.jpg

Facts

Week 7, 44 - 48 days, 13 - 17 mm

Gestational Age GA - week 9

Summary

  • Ectoderm: sensory placodes, lens pit, otocyst,nasal pits moved ventrally, fourth ventricle of brain
  • Mesoderm: heart prominence
  • Head: 1st, 2nd and 3rd pharyngeal arch, forebrain, eye, auricular hillocks
  • Body: heart, liver, umbilical cord
  • Limb: upper and lower limb buds, foot plate, wrist, hand plate with digital rays


See also Carnegie stage 18 Events

Features

  • Development indices: number of semicircular ducts (1-3) and length of the paramesonephric duct.
  • Identify: pigmented eye, eyelid, nasolacrimal groove, external acoustic meatus, heart, digital rays, liver prominance, thigh, ankle, foot plate, umbilical cord


Stage 18 Links: Week 7 | System Development | Lecture - Limb | Lecture - Head Development | Lecture - Sensory | Science Practical - Head | Science Practical - Sensory | Science Practical - Urogenital | Carnegie Embryos | Madrid Embryos | Category:Carnegie Stage 18 | Next Stage 19
  Historic Papers: 1911 larynx | 1948 stage 15-18


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

Stage18 bf10.jpg Stage18 bf11.jpg
Embryo in gestational sac Embryo open sac
Stage18 bf12.jpg Stage18 bf13.jpg
Embryo with placentation (ectopic) Embryo in amniotic sac
Stage 18 Links: Embryo in gestational sac | Embryo open sac | Embryo 2 and gestational sac | Embryo 2 | Carnegie stage 18


Embryo Virtual Slides

Stage 18 - Right Lateral

Stage18 bf11.jpg

 ‎‎Mobile | Desktop | Original

Stage 18 | Embryo Slides
Stage 18 - Left Lateral

Stage18 bf12.jpg

 ‎‎Mobile | Desktop | Original

Stage 18 | Embryo Slides

Scanning EM

Stage18 em01.jpgStage18 em11.jpg

Ventral view of head showing upper lip, maxilla and nasal region.

Image Source: Prof Virginia Diewert

Kyoto Collection

Stage18 bf1.jpg

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

Image source: Embryology page Created: 19.03.1999

Human stage18 face 01.jpg

Ventral view of head region (1 mm scale).

  • Kyoto Embryo 25783
  • right+yolk

    right+yolk

  • left+yolk

    left+yolk

  • left

    left

  • ventral

    ventral

  • right

    right

  • dorsal

    dorsal


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

Stage18 bf2.jpg Stage18 bf3.jpg Stage18 bf4.jpg Stage18 bf5.jpg

Stage18 bf6.jpg Stage18 bf7.jpg Stage18 bf8.jpg Stage18 bf9.jpg


Carnegie stage 18: Right | Anterior | Posterior | Left | Right | Anterior | Posterior | Left


Carnegie Collection Embryos - Stage 18 
Serial No. Size (mm) Grade Fixative Embedding Medium Plane Thinness (µm) Stain Semi. ducts P.-M. duct (mm) Year Notes
109 E., 12.0* Ch.,30 Poor Alc. P Transverse 20 Al. coch. 1 0.4 1897 Tubal Least—advanced third
144 E., 16.0* Ch, 40x30x30 Good Formalin P Sagittal 40 Al. eoch. 3 0.85 1899 Most—advanced third
175 E., 13.0 Ch, 30x25x25 Poor Alc. P Transverse 20 Al. coch. 2 0.6 1900 Tubal Partly macerated
296 E., 17.0 Poor Ale. P Coronal 20 Various 3 0.85 1905 Most—advanced third
317 E., 16.0 Good Formalin P Coronal 20 (Stain - Haematoxylin Eosin) or. G. 2 0.7 1905 Middle third
351 E.,14.0* Good Formalin P Coronal 250 Slightly carmine— 2 038 1904 Injected (Berlin blue)
406 E., 16.0 Ch., 40x40x40 Good Formalin P Sagittal 20 (Stain - Haematoxylin Eosin) 3 0.7 1907 Operative. Most—advanced third
423 E., 15.2 Good Formol—Zenker P Transverse 50 Carmine 3 0.85 1904
424 E., 172 Good Formalin P Transverse 50 Carmine 3 10 1904 Double infection. Advanced
492 E, 16.8 Ch, 40 x 40 Exc. Zenker P Coronal 40 Al. coch. v 3 0.7 1911 Injected (India ink)
511 E., 160* Ch., 3?* 32x32 Good Ale. P Sagittal 40 Al. coch. 3 1.1 1911 Head injured. Most advanced in group
670 E, 12.5 Poor Ale. P Sagittal 50 (Stain - Haematoxylin Eosin) 3 10 1913 Tubal Advanced
719 E, 15.0 Ch, 50x50x50 Good Formalin P Trans 40 Al. coch. 2 0.6 1913 Median in group
733 E., Ch., 4Sx40x2S ISO Poor Formalin P Sagittal 50 Al. coch. 2 0.6 1913 Median in group
841 E. 15.0 Ch., 18 x 16x9 Good Formalin P Coronal & Trans, 20 10 (Stain - Haematoxylin Eosin), carmine 2 0.32 1914 Operative. Head cut separately
899 E, 160* Ch. 50 x 18 x IS Good Bouin P Sagittal S0 Al. coch. 3 0,65 1914 Tubal Head injured
991 E. l?.0 Good Formalin P Sag so R, V, Gieson 3 0.9 1914 Advanced
1909 E., 14.6 Good Formalin P Coronal 20 Al. coch,or. G. 1 0.3 1917 Less advanced
2673 E.,15.5 Good Formalin P Transverse 40 Al. coch. 2 0.52 1919 Median in group
4430 E., 14.0 Ch, 51 x40x21 Exc. Corros. acetic P Transverse 15 Al. coch,or. G. 3 0.9 1923 Most—advanced third
5542B E., 16.0 Ch, 37x32x25 Good Formalin P Transverse 40 Al. coch. 2 0.7 1927 Other twin abnormal
5747 E, 15.2 Ch, 32x27x25 Poor Alc.—formol P Sagittal 25 Al. coch. 2 0.25 1928 Least—advanced or middle third
5935A E, 13.5 Ch, 40x30x30 Good Formalin P Coronal 40 Al. coch. 1 0.38 1929 Other twin stunted
6522 E, 13.2* Good Corros. acetic C—P Coronal 10 Al. coch. 3 0.8 7 Middle or most—advanced third
6524 E, 11.7* Exc. Corros. acetic C—P Transverse 10 Al. coch. 1 0.4 ? Least—advanced third
6525 E, 13.8* Exc. Corros. acetic C—P Sagittal 8 Al. coch. 2 0.42 ? Weak staining
6527 E, 14.4* Exc. Corros. acetic C—P Transverse 15 Al. coch. 2 0.67 ? Mechanical damage
6528 E, 13.4* Exc. Corros. acetic C—P Coronal 8 Al. coch. 1 0.33 ? Least—advanced third
6529 E, 15.6* Good Corros. acetic C—P Coronal 10 Al. coch. 2 0.4 .5 Middle third
6533 E, 12.5* Good Corros. acetic C—P Sagittal 6, 8, 10 Al. coch. 2 0.45 ? Middle third
6551 E, 18.0 Poor Formalin p Coronal 40 (Stain - Haematoxylin Eosin) 3 0.8 1932 Tubal
7707 E, 14.5 Ch ,37x32 Exc. Bouin C—P Transverse 10 (Stain - Haematoxylin Eosin), phlox. 2 0.54 1939 Operative. Middle third
8097 E, 15.5 Ch, 37x25x21 Good Formalin C—P Transverse 10 (Stain - Haematoxylin Eosin) 1 0.19 1942 Least advanced in group
8172 E, 16.5 Exc. Bouin C—P Transverse 20 (Stain - Haematoxylin Eosin) 3 0.58 1943 Operative. Very advanced
8235 E, 14.0* Good Bouin C—P Sagittal 10 (Stain - Haematoxylin Eosin) Mallory 2 0.25 1944 Tubal
8355 E, 15.0 Ch, 23 Exc. Formalin C—P Coronal 10 Azan 1946 Tubal. Duplicated spinal cord caudally
8812 E, 12_9 Exc Formalin C—P Transverse 10 (Stain - Haematoxylin Eosin) 1950 Rubella. Medical abortion. Midbrain punctured
8945 E, 13.9 Good Zenker p Transverse 8 Borax, carm. 1952 Univ. Chicago No. H 1254
9107 E, 17.0 Ch, 38x28x22 Good Bouin p Transverse 15 Borax, carm. 1918 Univ. Chicago No. H 516
9247 E, 15.0 Exc. Bouin C—P Sagittal 8 Azan 1954 Tubal
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).

Hill Collection

HillH6 Stage 18 bf05.jpg HillH6 Stage 18 bf04.jpg HillH6 Stage 18 bf03.jpg HillH6 Stage 18 bf02.jpg
right ventral right ventrolateral right ventrolateral right lateral
HillH6 Stage 18 bf51.jpg HillH6 Stage 18 bf06.jpg HillH6 Stage 18 bf01.jpg
right ventral (smaller) left lateral (smaller) right dorsolateral (smaller)
Links: Hill Collection

Madrid Collection

Madrid Collection Embryos  
Carnegie
Stage 		Embryo Days CRL (mm) Section
thickness 		Staining Section plane
18 GV-6 44 13 10 (Stain - Haematoxylin Eosin)-Azan transverse
18 Ve 44 13.5 10 (Stain - Haematoxylin Eosin) sagittal
18 JF2 45 14.5 10 (Stain - Haematoxylin Eosin)-trichrome transverse
18 NO 45 15 10 (Stain - Haematoxylin Eosin) transverse
18 J5 46 16.5 10 (Stain - Haematoxylin Eosin) frontal

Hinrichsen Collection

Hinrichsen S226 002.jpg

Embryo 226 Carnegie stage 18, 16 mm slide 20 (Sagittal, quality good, Stain ((Stain - Haematoxylin Eosin), Tri, Azan), total slides 114).

Digital Embryology Consortium - Hinrichsen Collection


Embryo ME53 Carnegie stage 18, CRL 16 mm, (Frontal whole Embryo, Stain ((Stain - Haematoxylin Eosin)), total slides 132).

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.

Events

  • vision - Mesenchyme invades the region between the lens epithelium and the surface ectoderm.[1]
  • hearing - otic capsule precartilaginous. Semicircular ducts form in the order anterior, posterior, and lateral from thickened epithelial areas and adjacent epithelial layers fuse. Cochlear duct is now L-shaped. First pharyngeal arch bar begins to chondrify (Meckel’s cartilage), second arch may chondrify (Reichert’s cartilage), stapes and stapedius commence. Auricular hillocks merge to form auricle primordia.
  • Bone - lower limb femur and tibia chondrification of cartilage template.[3]
  • endocrine[5]
    • Epiphysis - cellular migration in the pineal body forms a distinct "anterior lobe" in which follicles appear (Stadium 3 of Turkewitsch 1933) (O'Rahilly 1973 a).
    • thymus - thymus makes contact with the thyroid gland and contains a series of canals internally[6].
    • thyroid - median thyroid is in contact with "lateral thyroid components"[6] but others have maintained that the telopharyngeal body should not be regarded as a thyroid component (Bejdl and Politzer 1953). The lobes of the thyroid are "composed of series of continuously communicating solid annectent bars" (Weller 1933). This is "the earliest stage of the definitive thyroid" (ibid.). First differentiation occurs in Weller's (1933) "lateral thyroid component," which is beginning to "blend into uniformly constituted thyroid tissue". Weller (1933)[6] illustrated (Fig. 11) a thyroid gland that still showed continuity between its pedicle and the epithelium of the pharynx.
    • adrenal cortex - gland becomes reorganized. The C1, 2, and 3 cells form cords as sinusoids develop. Cells divide at or near the surface, where new cells are added.[7]
  • meninges (spinal cord) - vertebral canal clearly distinguishable from its wall, within which chondrification is rapidly advancing. Ventral migration of ganglia has continued, ventral extremities are entering the intervertebral foramina, dorsal extremities lie at about spinal cord mid-level. Meninx primitiva is loosening and spaces are becoming evident within it, particularly in the region ventral to the cord. Over the dorsal surfaces of the centra and the intervertebral disks the cells of the meninx primitiva are, for the first time, showing indications of stratification. This stratification is more evident over the intervertebral disks, where it extends laterally and then sweeps dorsad over the medial surface of the ganglia. Similar stratification appears in the pia mater, and this is particularly evident adjacent to the anterior longitudinal sulcus. These conditions are most pronounced in the cervical region and become less distinct in a caudal direction. The rudiments of the dentate processes now form denser and more restricted concentrations and can be identified in the interganglionic transverse sections, where they extend in a dorsoventral direction from the pia, slightly above the emergence of the ventral root, to the mid-point of the rudimentary pedicle.[8]
  • Renal - Collecting tubules develop from the calices at stages 17 and 18. They are surrounded by sharply outlined condensed primordia in the process of forming secretory tubules. Renal corpuscules are not yet present. By stage 18 the mesonephric duct and the ureter open almost independently into the vesico-urethral canal[9] : i.e., the common excretory duct is disappearing. The cloacal membrane is ready to rupture.[10]
  • genital[11]
    • Primordial Germ Cells, extragonadal germ cells were identified in gut epithelium from this stage.[12]rimordial germ cells were identified in the testis.
    • gonad forms a pronounced elevation and extends to the rostral pole of the mesonephros and the rete is beginning.[13]
    • testis gonadal blastema differentiates into testicular cords.[12]
    • ovary gonadal cords identifiable in the ovary.[14]
  • ventral body wall - separate intercostal and abdominal wall muscles differentiated, and ribs, sterna, and muscles began to expand ventromedially and caudally.[15]


References

  1. ↑ Pearson AA. (1980). The development of the eyelids. Part I. External features. J. Anat. , 130, 33-42. PMID: 7364662
  2. ↑ Bossy J. Development of olfactory and related structures in staged human embryos. (1980) Anat. Embryol., 161(2);225-36 PMID 7469043
  3. ↑ Mérida-Velasco JA, Sánchez-Montesinos I, Espín-Ferra J, Mérida-Velasco JR, Rodríguez-Vázquez JF & Jiménez-Collado J. (1997). Development of the human knee joint ligaments. Anat. Rec. , 248, 259-68. PMID: 9185992
  4. ↑ Hutchins GM, Kessler-Hanna A & Moore GW. (1988). Development of the coronary arteries in the embryonic human heart. Circulation , 77, 1250-7. PMID: 3286038
  5. ↑ 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
  6. ↑ 6.0 6.1 6.2 Weller GL. Development of the thyroid, parathyroid and thymus glands in man. (1933) Contrib. Embryol., Carnegie Inst. Wash. 24: 93-139.
  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.
  9. ↑ Shikinami J. Detailed form of the Wolffian body in human embryos of the first eight weeks. (1926) Contrib. Embryol., Carnegie Inst. Wash. Publ. 363, 18: 46-61.
  10. ↑ O'Rahilly R. and Müller F. Developmental Stages in Human Embryos. Contrib. Embryol., Carnegie Inst. Wash. 637 (1987).
  11. ↑ O'Rahilly R. (1983). The timing and sequence of events in the development of the human reproductive system during the embryonic period proper. Anat. Embryol. , 166, 247-61. PMID: 6846859
  12. ↑ 12.0 12.1 Jirásek JE. Development of the Genital System and Male Pseudohermaphroditism. (1971) Johns Hopkins Press, Baltimore.
  13. ↑ Wilson KM. Origin and development of the rete ovarii and the rete testis in the human embryo. (1926) Carnegie Instn. Wash. Publ. 362, Contrib. Embryol., Carnegie Inst. Wash., 17:69-88.
  14. ↑ Gillman J. The development of the gonads in man, with a consideration of the role of fetal endocrines and the histogenesis of ovarian tumors. (1948) Contr Embryol Carneg Instn. 32: 81-131.
  15. ↑ Mekonen HK, Hikspoors JP, Mommen G, Köhler SE & Lamers WH. (2015). Development of the ventral body wall in the human embryo. J. Anat. , 227, 673-85. PMID: 26467243 DOI.

Additional Images

  • Stage 18 Optical Projection Tomography

    Stage 18 Optical Projection Tomography

  • Stage 18 Heart MRI

    Stage 18 Heart MRI

  • External ear Stages 14-23 and adult

    External ear Stages 14-23 and adult

Historic Images

  • Human embryonic shoulder girdle

    Human embryonic shoulder girdle

  • 1921. Dural venous system human embryo 15 mm long

    1921. Dural venous system human embryo 15 mm long

  • 1921 Vascular system of the brain of the human embryo

    1921 Vascular system of the brain of the human embryo

  • Embryo 109 Sabin 1909 Fig. 4

    Embryo 109 Sabin 1909 Fig. 4

  • Fig. 273. Sagittal cut caudal end of embryo of 14mm

    Fig. 273. Sagittal cut caudal end of embryo of 14mm

  • 17 mm Embryo

    17 mm Embryo

Lisser H. Studies on the development of the human larynx. (1911) Amer. J Anat. 12: 27-66.

  • 1911 Cross section to show cricoid cartilage and M. criooarytaenoideus posterior.

    1911 Cross section to show cricoid cartilage and M. criooarytaenoideus posterior.

  • 1911 Cross section to show thyreoid cartilage, M. criooarytaenoideus lateralis,

    1911 Cross section to show thyreoid cartilage, M. criooarytaenoideus lateralis,

  • 1911 Sagittal section to show, especially, M. interarytaenoideus.

    1911 Sagittal section to show, especially, M. interarytaenoideus.

  • 1911 Sagittal section to show hyoid bone and thyreoid cartilage, M. cricothyreoideus, and tongue region

    1911 Sagittal section to show hyoid bone and thyreoid cartilage, M. cricothyreoideus, and tongue region

  • 1911 Sagittal section

    1911 Sagittal section


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


Cite this page: Hill, M.A. (2023, December 1) Embryology Carnegie stage 18. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Carnegie_stage_18

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