Embryonic Development: Difference between revisions
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{{Header}} | |||
== Introduction == | == Introduction == | ||
{| class="wikitable mw-collapsible mw-collapsed" | |||
{| class="wikitable collapsible collapsed" | ! Author Comments | ||
! Author Comments | |||
|- | |- | ||
| [[File: | | [[File:Mark_Hill.jpg|50px]] '''Start here''' by looking at the external appearance of embryos in sequence from [[#Carnegie_Stages|1 to 23]]. It is not so important to memorise the dates, as they are only approximate, but more important to understand '''growth''' (size changes) and the '''development''' (overall sequence of events) during this period. | ||
Clicking the Carnegie stage numbers opens a page dedicated to describing that single stage and the associated developmental events. | |||
|} | |} | ||
{| | {| | ||
| This page shows some key events of human development during the embryonic period of the first eight weeks (weeks 1 - 8) following fertilization. This period is also considered the organogenic period, when most organs within the embryo have begun to form. | | This page shows some key events of human development during the embryonic period of the first eight weeks (weeks 1 - 8) following fertilization. This period is also considered the organogenic period, when most organs within the embryo have begun to form. | ||
There are links to more detailed descriptions which can be viewed in a week by week format, by the Carnegie stages or integrated into a [[Timeline_human_development|'''Timeline of human development''']]. | There are links to more detailed descriptions which can be viewed in a week by week format, by the Carnegie stages or integrated into a [[Timeline_human_development|'''Timeline of human development''']]. | ||
Online resources | |||
Online resources include: individual images of all Carnegie stages, scanning electron micrographs of the earlier stages, cross-sections showing internal structures at mid- and late-embryonic, 3D reconstructions of internal structures, animations of processes, ultrasound scans and information about abnormalites of development. | |||
Note that there is variability in the actual timing of specific events and at the end of this period [[Fetal_Development|fetal development]] begins. | Note that there is variability in the actual timing of specific events and at the end of this period [[Fetal_Development|fetal development]] begins. | ||
| | {{Human Embryo - Biological definition 2006}} | ||
{{Carnegie_stage_table_1}} | |||
| valign=top| [[File:Embryo stages 01.gif]] | |||
|} | |||
{| | |||
! Kyoto Collection | |||
! width=5px| | |||
! Carnegie Collection | |||
|- | |- | ||
| [[File:Human Carnegie stage 1-23.jpg|alt=Kyoto Collection Embryos|link=Kyoto Collection|550px]] | |||
| | | | ||
| [[ | | [[File:Human Carnegie stage 10-23.jpg|alt=Carnegie Collection Embryos|link=Carnegie Collection|420px]] | ||
|- | |||
| Human Embryo, Carnegie stages 1-23 | |||
| | |||
| Human Embryo, Carnegie stages 10-23 | |||
|} | |} | ||
{| | |||
| width=380px|<html5media height="530" width="375">File:Embryo stages 003.mp4</html5media> | |||
| valign=top|Use the stage number links to images and information about each specific stage of human development over the first 8 weeks. The links below give a broad overview of developmental events during each week. | |||
[[File:Stage14compare23.jpg|200px]] | |||
[[ | |||
Embryo sizes - stage 14 compared to 23 | |||
{{Embryo stage movie 1}} | |||
{{Week}} | |||
:'''Links:''' [[Embryo Virtual Slides]] | [[Human Embryo Collections]] | [[Carnegie stage 13 - serial sections]] | [[Carnegie stage 22 - serial sections]] | |||
|} | |||
== Week 1 == | == Week 1 == | ||
[[Image:Early_zygote.jpg|thumb|Week 1 - Early zygote]] | [[Image:Early_zygote.jpg|thumb|link=zygote|Week 1 - Early zygote]] | ||
* [[Week 1]] Carnegie stage - | * [[Week 1]] Carnegie stage - {{CS1}} | {{CS2}} | {{CS3}} | {{CS4}} | ||
* | * {{oocyte}} | {{spermatozoa}} | {{fertilization}} | ||
* | * {{zygote}} | ||
* | * {{morula}} | ||
* | * {{blastocyst}} | ||
<br> | |||
{{Week 1 Links}} | |||
{| border='0px' | {| border='0px' | ||
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== Week 2 == | == Week 2 == | ||
[[File:Week2_001 icon.jpg|thumb|link= | [[File:Week2_001 icon.jpg|thumb|link=Implantation|Week 2 Implantation]] | ||
* [[Week 2]] Carnegie stage - [[Carnegie_stage_5|5]] | [[Carnegie_stage_6|6]] | * [[Week 2]] Carnegie stage - [[Carnegie_stage_5|5]] | [[Carnegie_stage_6|6]] | ||
* | * {{trophoblast}} - ({{trophectoderm}}) outer cell layer | ||
* [[Embryoblast]] - inner cell mass | * [[Embryoblast]] - inner cell mass | ||
* | * {{implantation}} | ||
* [[Bilaminar embryo]] | * [[Bilaminar embryo]] | ||
<br> | |||
{{Week 2 Links}} | |||
{| | {| | ||
! Carnegie stages | ! Carnegie stages | ||
|- | |- | ||
| [[File: | | [[File:HeuserStreeter1941 fig49.jpg|100px|link=Carnegie_stage_4]] | ||
| [[File: | | [[File:Stage5_bf11L.jpg|100px|link=Carnegie_stage_5]] | ||
| [[File:Stage6_bf03.jpg|100px|link=Carnegie_stage_6]] | |||
|- | |- | ||
| [[Carnegie_stage_4|stage 4]] | |||
| [[Carnegie_stage_5|stage 5]] | | [[Carnegie_stage_5|stage 5]] | ||
| [[Carnegie_stage_6|stage 6]] | | [[Carnegie_stage_6|stage 6]] | ||
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== Week 3 == | == Week 3 == | ||
[[Image:Stage7 features.jpg|thumb|Week 3 - Embryonic disc]] | [[Image:Stage7 features.jpg|thumb|link=Week 3|Week 3 - Embryonic disc]] | ||
* [[Week 3]] - Carnegie stage - [[Carnegie_stage_7|7]] | [[Carnegie_stage_8|8]] | [[Carnegie_stage_9|9]] | * [[Week 3]] - Carnegie stage - [[Carnegie_stage_7|7]] | [[Carnegie_stage_8|8]] | [[Carnegie_stage_9|9]] | ||
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* [[Neurogenesis]] | * [[Neurogenesis]] | ||
<br> | |||
{{Week 3 Links}} | |||
{| border='0px' | {| border='0px' | ||
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== Week 4 == | == Week 4 == | ||
[[File:Stage11_bf3b.jpg|thumb|120px|Week 4 - The heart begins]] | [[File:Stage11_bf3b.jpg|thumb|120px|link=Week 4|Week 4 - The heart begins]] | ||
* [[Week 4]] - Carnegie stage - [[Carnegie_stage_10|10]] | [[Carnegie_stage_11|11]] | [[Carnegie_stage_12|12]] | [[Carnegie_stage_13|13]] | * [[Week 4]] - Carnegie stage - [[Carnegie_stage_10|10]] | [[Carnegie_stage_11|11]] | [[Carnegie_stage_12|12]] | [[Carnegie_stage_13|13]] | ||
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* [[Placodes]] | * [[Placodes]] | ||
* [[Pharyngeal arches]] | * [[Pharyngeal arches]] | ||
<br> | |||
{{Week 4 Links}} | |||
{| border='0px' | {| border='0px' | ||
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== Week 5 == | == Week 5 == | ||
[[ | [[File:Stage14_bf2l.jpg|thumb|link=Week 5|Week 5 embryo]] | ||
* [[Week 5]] - Carnegie stage - [[Carnegie_stage_14|14]] to [[Carnegie_stage_15|15]] | * [[Week 5]] - Carnegie stage - [[Carnegie_stage_14|14]] to [[Carnegie_stage_15|15]] | ||
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== Week 6 == | == Week 6 == | ||
[[File:Stage16-18_face.jpg|thumb|Week 6 - Early face deevelopment]] | [[File:Stage16-18_face.jpg|thumb||link=Week 6|Week 6 - Early face deevelopment]] | ||
* [[Week 6]] - Carnegie stage - [[Carnegie_stage_16|16]] to [[Carnegie_stage_17|17]] | * [[Week 6]] - Carnegie stage - [[Carnegie_stage_16|16]] to [[Carnegie_stage_17|17]] | ||
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== Week 7 == | == Week 7 == | ||
[[File:Stage19_bf2b.jpg|thumb|150px|Week 7 - Head and limb development]] | [[File:Stage19_bf2b.jpg|thumb|150px||link=Week 7|Week 7 - Head and limb development]] | ||
* [[Week 7]] - Carnegie stage - [[Carnegie_stage_18|18]] to [[Carnegie_stage_19|19]] | * [[Week 7]] - Carnegie stage - [[Carnegie_stage_18|18]] to [[Carnegie_stage_19|19]] | ||
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== Week 8 == | == Week 8 == | ||
[[File:Stage23_bf1c.jpg|thumb|Week 8 - Last embryonic stage 23]] | [[File:Stage23_bf1c.jpg|thumb||link=Week 8|Week 8 - Last embryonic stage 23]] | ||
* [[Week 8]] - Carnegie stage - [[Carnegie_stage_20|20]] | [[Carnegie_stage_21|21]] | [[Carnegie_stage_22|22]] | [[Carnegie_stage_23|23]] | * [[Week 8]] - Carnegie stage - [[Carnegie_stage_20|20]] | [[Carnegie_stage_21|21]] | [[Carnegie_stage_22|22]] | [[Carnegie_stage_23|23]] | ||
* Last week of embryonic development. | * Last week of embryonic development. | ||
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{{Carnegie stage table}} | {{Carnegie stage table}} | ||
==References== | |||
<references/> | |||
{{Glossary}} | {{Glossary}} | ||
{{Footer}} | {{Footer}} | ||
[[Category:Human Embryo]][[Category:Human]] | |||
[[Category:Week 1]][[Category:Week 2]][[Category:Week 3]][[Category:Week 4]] | |||
[[Category:Week 5]][[Category:Week 6]][[Category:Week 7]][[Category:Week 8]] |
Latest revision as of 06:46, 13 December 2018
Embryology - 17 Jun 2024 ![]() ![]() ![]() |
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Introduction
Author Comments |
---|
![]() Clicking the Carnegie stage numbers opens a page dedicated to describing that single stage and the associated developmental events. |
This page shows some key events of human development during the embryonic period of the first eight weeks (weeks 1 - 8) following fertilization. This period is also considered the organogenic period, when most organs within the embryo have begun to form.
|
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Kyoto Collection | Carnegie Collection | |
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Human Embryo, Carnegie stages 1-23 | Human Embryo, Carnegie stages 10-23 |
<html5media height="530" width="375">File:Embryo stages 003.mp4</html5media> | Use the stage number links to images and information about each specific stage of human development over the first 8 weeks. The links below give a broad overview of developmental events during each week.
Embryo sizes - stage 14 compared to 23
Embryo Week: Week 1 | Week 2 | Week 3 | Week 4 | Week 5 | Week 6 | Week 7 | Week 8 | Week 9 |
Week 1
- Week 1 Carnegie stage - 1 | 2 | 3 | 4
- oocyte | spermatozoa | fertilization
- zygote
- morula
- blastocyst
Week 1 Links: stage 1 | stage 2 | stage 3 | menstrual cycle | fertilization | zygote | morula | blastocyst | Lecture - Fertilization | meiosis | mitosis | Lecture - Week 1 and 2 | menstrual cycle | oocyte | spermatozoa | twinning | Genetic risk maternal age | Trisomy 21 | Trisomy 18 | Trisomy 13 | hydatidiform mole | GA week 3 |
Carnegie stages | |||
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stage 1 | stage 2 | stage 3 | stage 4 |
Week 2
- Week 2 Carnegie stage - 5 | 6
- trophoblast - (trophectoderm) outer cell layer
- Embryoblast - inner cell mass
- implantation
- Bilaminar embryo
Week 2 Links: stage 4 | stage 5 | stage 6 | Lecture - Week 1 and 2 | implantation | trophoblast | human chorionic gonadotropin | pregnancy test | twinning | Category:Week 2 | GA week 4 |
Carnegie stages | ||
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stage 4 | stage 5 | stage 6 |
Week 3
Week 3 Links: stage 7 | stage 8 | stage 9 | Gastrulation | Endoderm | Mesoderm | Ectoderm | Placenta | Coelomic Cavity | Lecture | Category:Week 3 | GA week 5 |
Carnegie stages | ||
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stage 7 | stage 8 | stage 9 |
Week 4
Week 4 Links: stage 10 | stage 11 | stage 12 | 13 | Placodes | Pharyngeal arches | Lecture - Mesoderm | Lecture - Ectoderm | Lecture - Early Vascular | Category:Week 4 | GA week 6 |
Carnegie stages | |||
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stage 10 | stage 11 | stage 12 | stage 13 |
Week 5
Carnegie stages | |
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stage 14 | stage 15 |
Week 6
Carnegie stages | |
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stage 16 | stage 17 |
Week 7
Carnegie stages | |
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stage 18 | stage 19 |
Week 8
Carnegie stages | |||
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stage 20 | stage 21 | stage 22 | stage 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
Carnegie Stage Table
Weeks shown in the table below are embryonic post ovulation age, for clinical Gestational Age (GA) measured from last menstrual period, add 2 weeks.
(not to scale) |
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fertilized oocyte, zygote, pronuclei | |||
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morula cell division with reduction in cytoplasmic volume, blastocyst formation of inner and outer cell mass | |||
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loss of zona pellucida, free blastocyst | |||
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attaching blastocyst | |||
(week 2) |
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implantation | ||
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extraembryonic mesoderm, primitive streak, gastrulation | |||
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gastrulation, notochordal process | |||
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primitive pit, notochordal canal | |||
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Somitogenesis Somite Number 1 - 3 neural folds, cardiac primordium, head fold | |||
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Somite Number 4 - 12 neural fold fuses | |||
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Somite Number 13 - 20 rostral neuropore closes | |||
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Somite Number 21 - 29 caudal neuropore closes | |||
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Somite Number 30 leg buds, lens placode, pharyngeal arches | |||
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lens pit, optic cup | |||
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lens vesicle, nasal pit, hand plate | |||
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nasal pits moved ventrally, auricular hillocks, foot plate | |||
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finger rays | |||
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ossification commences | |||
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straightening of trunk | |||
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upper limbs longer and bent at elbow | |||
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hands and feet turned inward | |||
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eyelids, external ears | |||
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rounded head, body and limbs | |||
The embryos shown in the table are from the Kyoto and Carnegie collection and other sources.
References
- ↑ Findlay JK, Gear ML, Illingworth PJ, Junk SM, Kay G, Mackerras AH, Pope A, Rothenfluh HS & Wilton L. (2007). Human embryo: a biological definition. Hum. Reprod. , 22, 905-11. PMID: 17178746 DOI.
- ↑ O'Rahilly R. 1979. Early human development and the chief sources of information on staged human embryos. Europ. J. Obstet. Gynec. Reprod. Biol., 9, 273-280. PMID 400868
- ↑ O'Rahilly R. and Müller F. Developmental Stages in Human Embryos. Contrib. Embryol., Carnegie Inst. Wash. 637 (1987).
Glossary Links
- Glossary: A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | Numbers | Symbols | Term Link
Cite this page: Hill, M.A. (2024, June 17) Embryology Embryonic Development. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Embryonic_Development
- © Dr Mark Hill 2024, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G