- #1
Silicon Waffle
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Take for example a fetus of 2 weeks old and a baby of 2 years old. The fetus doesn't show any limbs, skull. How do I know that is a human fetus ? 
Gene expression for bigger limbs
- Thread starter Silicon Waffle
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Discussion Overview
The discussion revolves around the identification of species at various embryonic stages, particularly focusing on the expression of genes related to limb development. Participants explore the challenges of distinguishing between human and animal embryos before significant morphological features are present.
Discussion Character
- Exploratory
- Conceptual clarification
- Debate/contested
Main Points Raised
- One participant questions how to identify a human fetus at 2 weeks old, noting the absence of limbs and skull.
- Another participant asserts that by the time an embryo develops into a fetus, limbs are present in healthy cases, prompting a request for clarification on the initial question.
- A participant corrects their earlier statement about developmental stages, indicating a focus on embryos rather than fetuses.
- Concerns are raised about identifying species based on a tiny embryo, given the limitations of morphological features at that stage.
- DNA testing is suggested as a method for species identification, though one participant questions the practical scenarios for such identification.
- Another participant emphasizes that all embryos possess the same genetic material from fertilization, but gene expression varies, affecting phenotypic outcomes.
- There is uncertainty expressed about the feasibility of differentiating species based on early-stage embryos.
Areas of Agreement / Disagreement
Participants do not reach a consensus on the methods for identifying species at early embryonic stages, and multiple viewpoints regarding gene expression and identification challenges remain present.
Contextual Notes
Participants highlight limitations in identifying species based on morphological features at early developmental stages and the role of gene expression in determining phenotypic differences.
Who May Find This Useful
This discussion may be of interest to those studying developmental biology, genetics, or embryology, particularly in the context of species identification and gene expression.
- #2
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By the time an embryo forms into a foetus the head, arms and legs are all present (in healthy cases). What is the basis for your question?
- #3
Silicon Waffle
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Oh 
so sorry for my incorrect developmental stage, I should have meant the embryo
http://embryo.soad.umich.edu/carnStages/allStagesButtons.gif
The baby will not have any legs after 2 weeks (14 days). How could you identify whether it's either a human or some animal embryo given that you are not allowed to wait till it becomes bigger ?
so sorry for my incorrect developmental stage, I should have meant the embryohttp://embryo.soad.umich.edu/carnStages/allStagesButtons.gif
The baby will not have any legs after 2 weeks (14 days). How could you identify whether it's either a human or some animal embryo given that you are not allowed to wait till it becomes bigger ?
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- #4
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DNA testing would reveal what species it is. I have to ask though under what circumstances do you envision being given a random embryo and asked to identify the species?
- #5
Silicon Waffle
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Thanks Ryan_M_B.Ryan_m_b said:
I am learning how to identify species in each developmental stage. I don't know what genes expressed to grow a limb in the embryo and because a tiny embryo still doesn't have all genes like an adult does, DNA barcoding so may not work. I don't know if that is true.
- #6
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From the moment an egg is fertilised it has all the genes it is ever going to have. Adults, babies, foetuses and embryos all have the same genes. The difference is in the expression of those genes, both in time and space. Simply put when a gene is expressed it is "on", when it is not expressed it is "off". A nerve cell has the same genes as a muscle cell but they express different genes making them different phenotypically. Good luck with your attempt, I'm not sure how easy it is to differentiate species by looking at their foetuses, especially in the early stages.
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