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Questions tagged [embryology]

The study of the development of an embryo from fertilisation through to description as a foetus.

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Could bone marrow transplants be used to prevent tissue rejection of trans-species organs?

So the immune system doesn't calibrate (for want of a better euphemism) to recognize it's own cells until fairly well along in fetal development & the major components of the immune system (...
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Is the allantois considered a part of the placenta?

Is the allantois considered a part of the placenta? I know that it connects the embryo with the placenta and it eventually becomes a part of the vein in the umbilical cord.
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Real embryo pictures: How different zones(speeman organizer, marginal zones…) are known?

In many textbook, figures of embryo are drawn,but in reality how biologist know which zone is this one of an embryo in gastrulation stade? Except the dorsal lip here i can't localize other thing.
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Fertilization of the human egg- where does our centrosome come from?

Is there a centrosome in a human egg cell? Is the reason why the egg cell remains paused before meiosis 2 because there isn't a centrosome, and it only divides when the sperm fertilizes it thus it can ...
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How does axon guidance system precisely targets specific axons?

Axons find their way to the terminus by responding to axon guidance molecules (AGMs) that attract and repel growth cones or make them stir. This I understand. Through a very specific combination of ...
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The effect of incubation on mammalian phenotype

The example I had in mind: say, we fertilized a chihuahua ovum with a Caucasian shepherd sperm in vitro (two dog breeds with vastly different phenotypes - and I imagine, with different incubation ...
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Can a brain process auditory signals at 18 weeks of human development?

According to When a fetus hear , When a baby can hear in the womb and several other similar articles at week 18th a baby starts to hear sound. And according to How hearing works. Hearing involves ...
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Dynamic of the number of cells over time as the embryo grows

I would like to investigate the dynamic of the number of cells over time as the embryo grows. I am interested in any multicellular animal species for which we can have some data. How does the number ...
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Can a viable embryo develop from the fusion of two egg cells?

For a zygote to form, two haploid gametes undergo meiosis and fuse during fertilisation. Since two egg cells (or even two sperm cells) are both haploid, is it theoretically possible for them to make ...
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How can there not be purpose movement in the fetus until week 18, when a fetus can open its mouth and suck its fingers at week 11?

According to Fetal Movement According to an overview produced by the Royal College of Physicians of Edinburgh, purposive movement begins at about 18 weeks, gradually replacing reflex movements ...
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212 views

difference between blastula and blastocyst

What is the difference between these 2 terms. I believe that blastocyst is for animals, but structurally is there any difference? And how would you be able to identify each?
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How does gene affect organs development in eukaryotic cells? [closed]

I'm totally new to biology and apologies if you find this basic. The central dogma insists that genetic information flows in this direction: DNA -> RNA -> proteins So far so good, it is very clear ...
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361 views

What is the difference between apomixis, agamospermy and apospory?

Some websites say agamospermy is just a synonym of apomixis but the definition of both terms is different. Others give almost same definition of apospory and agamospermy while also saying that ...
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What are limitations of giving birth to a baby from a frozen embryo?

Recently the story of a woman giving birth to baby girl from an embryo frozen 24 years ago hit the news. After an in vitro fertilization the embryo was frozen on 14 October 1992( Article in the ...
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Does the mesoderm evolve from the ectoderm or the endoderm?

I know the embryos of most animals develop into 3 germ layers. However primitive animals, such as Cnidarians, only have 2 germ layers - they lack a mesoderm. Therefore the 3rd germ layer must have ...
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42 views

Cell differentiation by non-identical copies

There are in principle two ways that two cells with the same mother cell can differentiate/specialize/diverge: Because they are not perfect identical copies (= different internal influencing factors)....
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Why does cell differentiation start with the morula?

I suppose that cell differentation has to start by some external symmetry breaking. The first time there are two different types of cells is the morula with roughly 16 cells: there are some 12-15 ...
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Shell-less Chick development - Incorporation of Calcium carbonate instead of Calcium lactate pentahydrate powder?

I'm a college undergrad biology student and currently studying developmental biology as part of my curriculum. I've read a research journal titled, A Novel Shell-less culture system for chick embryo ...
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I need a site for online courses

I need a site which has online courses for anatomy of limb and head and neck and also embryology, so far I have used www.coursera.org and it was really organized and helpful but unfortunately it does ...
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Are there predefined implantation sites in mammalian uterus?

I do surgical embryo transfer of genetically modified (microinjected) mouse embryos (at 1 or 2 cell stage). As most of the constructs are new, we expect that it may affect birth rate. In case there ...
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842 views

Has the gestation (pregnancy) period for humans always been 9 months?

At this point in our evolutionary progress, the expected human gestation period is (roughly) nine months long. My question is, has this duration of time always been the same for homo sapiens? Or, are ...
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How necessary is human zygote cytoplasm for generating a human?

I'm primarily questioning the roles of genetics and cytoplasmic factors of zygote in generating a human being with a natural embryological process. For instance, is there an experiment where we check ...
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Can 12 mitotic divisions produce 6000 nuclei?

The following quote is from "Principles of Development" by Tickle & Wolpert: "After fertilization and fusion of the sperm and egg nuclei, the zygote nucleus undergoes a series of rapid mitotic ...
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Is the blastopore imaginary?

I've been told in my zoology class that the blastopore is an imaginary pore found in gastrula, from which mouth develops first in protostomes and anus develops first in deuterostomes. But we've also ...
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Are there any studies detailing the overall “-omics” effects of using bleach to synchronise a C. elegans population?

I wasn’t able to find papers detailing the changes in the transcriptome/proteome of C. elegans when synchronised by bleaching vs not-bleaching. Hopefully someone can point me in the right direction!
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At what stage is the nervous system developed enough to interpret neuronal signals as 'pain'?

According to this article in Live Science, one of the reasons the fetus can't feel pain until 19 weeks is because the nervous system isn't fully developed. But according to this article, the heart ...
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Is a part of the spinal cord from the mesoderm?

The caudalmost part of the neural tube is formed by the caudal eminence. Isn't this mesodermal? So does it mean that, a part of the spinal cord is mesodermal in origin? Does it have any significance ...
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Where does craniocaudal closure of anterior neuropore start?

Closure of the cranial neuropore is bidirectional, and final closure occurs in the area of the future forebrain. Closure of the caudal neuropore is strictly craniocaudal and finishes at the level of ...
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Mental Symphysis

Why dow we consider mandibular symphysis(symphysis menti) as type of Amphiarthrosis that too of symphysis variety, eventhough it lacks movement and cartilage at joint? Why don't we consider as ...
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Why are sutural bones more common in lambdoid suture? [closed]

Why are sutural bones (Wormian bones) are more commonly present at lambdoid suture? Is the tortuous nature of lambdoid suture a reason for that? Evidences for my claim: They(sutural bones) occur ...
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What is this part of blastula called and how is endoderm formed?

Could you tell me what the yellow mass within the blastocoel is called ? I know that blastocoel is a fluid filled cavity, so are the yellow coloured cells the inner part of blastoderm or are they some ...
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What is the difference between Totipotent cells and Pluripotent cells? [duplicate]

I read the Wikipedia article about Cell Potency (Article on Cell Potency) Totipotency is the ability of a single cell to divide and produce all of the differentiated cells in an organism. while ...
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What are the chances that the contraceptive pill will cause death of human zygote? [closed]

The preventative pill, as I understand it, can cause zygotes to fail to attach to the uterine wall, or pry them off of it. Ignoring any and all ethical implications, what are the chances that this ...
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Why does rotational cleavage take place in mammels like humans. What is its significance? [closed]

What is the actual reason behind the rotational cleavage that takes place in humans? Why does it happen? If it doesn't occur, what will happen
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How do genes code for differences in arms and legs?

So to me it seems like arms and legs are pretty similar that they almost have the same blueprint. And if you change part of it like the number of digits, you will have 12 fingers and 12 toes. But at ...
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773 views

Is there a difference between an organizer and inducer substance?

There is a question in my Embryology textbook's exercise that asks about an organizer and inducer substance. I found their definitions and now I am wondering if they are the same things?
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Can only fully matured sperm fertilize an egg?

Are only mature sperm able to fertilize an egg? If so, is there typically a reserve of mature sperm that are saved after an ejaculation or does a male need to wait for new sperm to mature before ...
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What is the difference between endometrial lining and endometrial stroma?

This is in the context of embryology whereby the syncytiotrophoblast erodes the endometrial stroma during the penetration and implantation of the zygote. But I don't know the correct terminology of ...
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Are the human placenta chorionic villi and villous tree the synonyms?

Are the human placental chorionic villi and the villous tree the synonyms? Or, if not, can I say that these tissues would have practically the same gene expression profile in an RNA microarray ...
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329 views

How far is stem cell research from being to generate a new organ?

How far are we from being able to use stem cell research to generate a sperm, a heart, a liver, and a kidney? In stem cell research, my understanding is that you must start off with some cell to ...
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What is cytoplasmic localization?

I was studying development of chick but didn't understand what is cytoplasmic localization. My book says: After third cleavage , the rest of the cleavages are irregular and completely delimited ...
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Myoblasts Formation

Myoblasts arise from mesenchymal stem cells (MSCs), and are precursors to myocytes. In muscles, in the basement membrane, there are also present satellite cells which can divide to generate muscle ...
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Can a chicken really be hatched outside of the egg?

This YouTube video (screenshots attached) claims to show Japanese schoolchildren breaking an egg into a kind of clingfilm "hammock in a cup", and then growing and hatching a chick from it in an ...
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Mesoderm vs Mesenchyme- what's the difference?

My embryology textbook states that mesoderm can exist as Mesenchyme or Epithelium. I'm not sure what 'epithelium' means. Here is a quote for context: Somatic, splanchnic, and somite mesoderm can be ...
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What is the difference between the neural tube and the dorsal ventral cord?

I was wondering what the difference is between the neural tube and the dorsal ventral cord. I know that the neural tube forms during embryonic development from the ectoderm layer that folds inwards. ...
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992 views

why is the cleavage in frogs holoblastic and not meroblastic?

background information The cleavage of the frog embryo during the embryo development is holoblastic (complete cleavage). However when we look at yolk-rich eggs we see a cleavage pattern which is ...
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How is bilateral asymmetry determined in embryonic development?

What are the mechanisms that ensure consistent left-right asymmetric placement of various internal organs (heart, liver, etc) or consistent left-right asymmetric development of paired organs (brain, ...
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134 views

Embryo development terms

I'm trying to couple the following terms: cytoplasmic determinants, induction, positional information, hox genes, pattern information, morphogenisis, determination and differentiation. I hope ...
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13k views

How scientists can be confident that human embryo tail is really a tail?

From Wikipedia: Human embryos have a tail that measures about one-sixth of the size of the embryo itself. As the embryo develops into a fetus, the tail is absorbed by the growing body. How are we ...
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225 views

Does a zygote express all genes?

If a zygote has all the cytoplasmic determinants and all the specific transcription factors, does that mean that all genes in the genome are expressed?