Questions tagged [embryology]

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

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During the cleavage cycle of a zygote what determines where the blastula starts folding?

If all of the cells divide from the same zygote it seems like they should all be the same. What causes one part of the clump of cells in a blastula to start folding over to form the mesoderm and ...
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Does the prefrontal cortex fold over the diencephalon (limbic lobe) during embryogenesis?

The frontal lobe as the top of the vertebrate brain, does it fold over the diencephalon during embryogenesis and development of the brain?
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Is SCNT possible with only the nucleus of a somatic cell (rather than a whole somatic cell)?

The following figure from Life: The Science of Biology (11th edition) explains how SCNT (somatic cell nuclear transfer) was used in the cloning of Dolly: (The original paper about cloning Dolly - ...
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Why can early embryos survive freezing?

According to this Blastocyst & Embryo Freezing in IVF Embryos can be frozen at the pronuclear stage (one cell), or at any stage after that up to and including the blastocyst stage (5-7 days ...
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How does a cell distinguish left from right?

Although the human body is mostly left-right symmetrical, it consistently has asymetries. The heart is consistently slightly to the left side of the body. The liver is consistently on the right side. ...
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Modern views on the correspondence of moles

In his Memoirs, Casanova wrote: In the midst of the dimple which added such a charm to her chin Esther had a little dark mole, garnished with three or four extremely fine hairs. These moles, which ...
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Schizocoely and Enterocoely

In terms of phyla, mollusca, annelida and arthropoda are schizocoelic, whereas echinodermata and chordata are enterocoelic. I know that their difference lies in the formation of the coelom but how ...
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47 views

When do the first neurons appear in humans?

According to this Neural Plate The neural plate appears in day 18 in humans (very specific). and according to this Neural Plate (wiki) The progenitor cells that make up the precursors to neural ...
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What is the outer boundary of oligodendrocyte myelination?

The sensory and motor neurons comprising the spinal cord and brain stem have the interesting property that different structural components belonging to the same neuron can occupy both the PNS and CNS. ...
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How does the zygote divide much faster than other cells?

Normally a cell has a mechanism that controls its division. As far as I know, it checks surface area and stuff like that to decide to go for mitosis or not. However, this is not the case for a zygote....
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Do birds require cilia for left/right symmetry during their embryological stages?

I know that in humans ciliary dyskenisia can lead to a Situs inversus, is this also the case for birds and reptilians?
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Does the yolk sac for Danio rerio form at the vegetal pole?

Does the yolk sac in general form always at the vegetal pole? If so, is this the case for Danio rerio (the zebrafish)?
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When does the brain stem appear in humans?

This article states: Once the neural tube closes, at around week 6 or week 7 of pregnancy, it curves and bulges into three sections, commonly known as the forebrain, midbrain and hindbrain. ...
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How does a cell identify itself?

In embryological development, undifferentiated cells developed into specific types. As far as I understand, a key differentiating factor is the regulation of gene expression via transcription factors....
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If DNA methylation inactivates genes, does DNA demethylation activate them?

DNA demethylation can be passive or active. The passive process takes place in the absence of methylation of newly synthesized DNA strands by DNMT1 during several replication rounds – for example, ...
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Has an ectopic pregnancy's blastocyst ever been made to implant?

Has an ectopic pregnancy's blastocyst ever been successfully extracted from the Fallopian tube and made to implant in the uterus?
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How to supply oxygen to a culture vessel?

I'm reading this paper: https://www.jstage.jst.go.jp/article/jpsa/51/3/51_0130043/_pdf From day 17 of the culture period until hatching, pure oxygen was supplied at a flow rate of approximately 500 ...
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Ploidy of Central cell in embroidery sac

In the unfertilized embryo sac in angiosperms, is the central cell considered to be haploid or diploid? though it has two polar nuclei but both of them are haploid, so I don't think it can be ...
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Archenteron vs Gastrocoele

What is Difference between “Archenteron” and “Gastrocoele”. Are they same or different? Gastrula is characterized by Archenteron or Gastrocoele or Both?
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Why is cartilage replaced by bones in a vertebrate adult?

Why is cartilage present in a vertebrate embryo replaced by bones in an vertebrate adult even though cartilage can also provide me the structural framework like as in Chondrichthyes and they seem to ...
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What is the optimal time to implant embryo in uterus for in vitro fertilization?

What is the best time to implant an embryo in the uterus. I was under the impression that the earlier the better and more natural, but also if you wait until the blastocyst age, it may be better to ...
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What type of movement is “spontaneous movement” if it isnt reflex movement and it isnt purposive movement?

According to Spontaneous and induced fetal activity Spontaneous motor activity of the foetus depends significantly ot the foetal age; during the period between the 12th and 16th week it was ...
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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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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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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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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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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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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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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 ...