K12 Comparative Embryology: Difference between revisions
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| valign=top|N. Hartsoeker (1694) image of how he imagined a sperm would look if it contained a preformed individual. | | valign=top|N. Hartsoeker (1694) image of how he imagined a sperm would look if it contained a preformed individual. | ||
Note that Hartsoeker later rejected this preformationist view, carrying out calculations of size that showed that if all of the animals of any species had been enclosed in the first male or female, those animals that now inhabit the earth would have to be infinitely and incomprehensively small. | Note that Hartsoeker later rejected this preformationist view, carrying out calculations of size that showed that if all of the animals of any species had been enclosed in the first male or female, those animals that now inhabit the earth would have to be infinitely and incomprehensively small. | ||
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| Ernst Haeckel (1834 – 1919) "ontogeny recapitulates phylogeny" claimed that an individual organism's biological development (ontogeny), parallels and summarises its species evolutionary development (phylogeny). | | Ernst Haeckel (1834 – 1919) "ontogeny recapitulates phylogeny" claimed that an individual organism's biological development (ontogeny), parallels and summarises its species evolutionary development (phylogeny). | ||
First a single-celled organism, then evolve into a fish, then an amphibian, then a reptile, then a bird, and finally reach a mammal. | First a single-celled organism, then evolve into a fish, then an amphibian, then a reptile, then a bird, and finally reach a mammal. |
Revision as of 13:51, 29 March 2016
Embryology - 29 Mar 2024 Expand to Translate |
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Introduction
All human and animal embryos go through very similar stages of early development.
The major difference appears to be how long it takes to reach each of these same stages. We now also know that many of the underlying signals that regulate development are the same between these different species. This page will introduce how we can compare the development of different animal embryos.
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<html5media height="505" width="400">File:Embryo stages 003.mp4</html5media>
Click Here to play on mobile device This movie shows human embryo development between week 4 to 8 after fertilisation. |
Human Carnegie Stages
Exercise 1 - Embryo Size | |
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How big is the human embryo? Download and Print the Worksheet
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Week 4 to 5
This is what the human embryo looks like at the end of week 4 and the beginning of week 5 development (called Carnegie stage 13) about half way through embryonic development.
Measuring embryo size (Crown Rump Length) | Surface bulges (internal and external development) |
- Links: Carnegie Stages
Species Comparison of Carnegie Stages
This table shows a comparison between different animal embryos and human embryos using the same staging criteria. Note that researchers have also developed embryo staging criteria that is specific to a single species.
Exercise 2 - Embryo Stages Comparison | |
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How long do different species take to reach the same stage of development? Download and Print the Worksheet
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Human and Mouse Embryo
The images below show a human and mouse embryo that appear externally close to the same stage of development.
- Would you know which was which without the labels?
Human
37 - 42 days, Week 6, 8 - 11 mm CRL (Carnegie stage 16)
Mouse
11.5 days, Week 2, 6 - 7 mm CRL (Theiler Stage 19)
Exercise 3 - Embryo Comparison | |
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What features do different embryos share? Download and Print the Worksheet
The images below show the 4 views of the same embryo at about the same external stage of development.
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Early Development
Limb Comparative Anatomy
This cartoon shows the comparative anatomy of bones within the upper limb of 4 different species.
Each limb is significantly different in size and function, but all contain the same basic skeletal structures.
Animal Development
The table below lists the approximate development time for a large number of different animals, ranging from the opossum at 12 days to the elephant at 660 days.
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Animal Notes and Table Data Sources
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Teacher Note | |
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Currently only a series of related images.
I am writing explanatory notes and associated exercises for this section when I have some spare time. You can also let your students look at the animal pages designed by my students back in 2009. Each page includes images of the embryos and a timeline of development for each animal embryo. These are university undergraduate student designed pages describing the development of specific animal embryos.
ANAT2341 group projectsProject 1 - Rabbit | Project 2 - Fly | Project 3 - Zebrafish | Group Project 4 - Mouse | Project 5 - Frog | Students Page | Animal Development |
Teacher Note | ||||||
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Comparative Embryology - Links out to other resources.
K12 Student worksheetsThese worksheets have been designed as short teaching exercises that can be downloaded and printed (PDF version) or modified by the teacher (Word version) for use in class. Biology curriculum may vary between classes, state and country as a Teacher please check the materials closely before using for teaching purposes.
Worksheets Word: Comparative Embryology - Embryo Size | Embryo Stages | Embryo Species
Additional worksheets are currently being developed. These links below are not yet organised in a way that students can easily use (content level and navigation) bookmark this current page or use the browser back button. Look through the stages and tables and think about designing exercises comparing the different species.
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Developmental Misconceptions
Preformationist Theory | |
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N. Hartsoeker (1694) image of how he imagined a sperm would look if it contained a preformed individual.
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Recapitulation Theory |
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Ernst Haeckel (1834 – 1919) "ontogeny recapitulates phylogeny" claimed that an individual organism's biological development (ontogeny), parallels and summarises its species evolutionary development (phylogeny).
Cite this page: Hill, M.A. (2024, March 29) Embryology K12 Comparative Embryology. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/K12_Comparative_Embryology
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