Questions tagged [embryology]

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

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When does the human fetus gain conciousness?

At what week of pregnancy does the human fetus gain conciousness and feel pain? I've read the fetus in the womb tries to move its limbs and looks at its limbs trying to figure out what they are here. ...
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How do mothers handle acid from embryo bone mineralization?

This is a relatively trivial question, but, I have not seen it discussed much. It could be one factor in the "acidosis of pregnancy" (JAMA, 1929). Are the compensatory mechanisms measurable, ...
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Is there a realtime molecular clock within the genome to co-ordinate the developmental sequences in an embryo?

It is difficult to assume that the massive number of co-ordinated developmental sequences in a developing embryo is controlled by molecular signalling alone. Is anyone aware of a molecular or ...
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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, a baby starts to hear sounds at week 18. And according to How hearing works. Hearing involves ...
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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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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 Saccus in Embryology?

The word seems to be of German origin. I have it here Saccus lymphaticus inguinalis, Saccus lymphaticus jugularis, Saccus lymphaticus posterior, Saccus lymphaticus retroperitonaealis. I ...
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Where does Embryo Implantation occur? [closed]

Where does the embryo get implanted? If it is in the uterus side wall, why is the embryo shown hanging from top in some pictures?
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What factors make iSCNT less effective than SCNT?

When comparing the efficiency of SCNT vs iSCNT, specifically what percent of transfers that generate a living animal; it appears that genetic distance between the receiving cytoplasm and the donor ...
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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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Could bone marrow transplants help make xenotransplants viable?

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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Function of the mesentary in segmented worms?

The mesentary that appears at some phyla at some point in evolution, initially, what exact function does it have?
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How do pseudo-coelomates solve what the mesentary later evolve to do?

Pseudo-coelomates have evolved a coelom, but, lack the mesentary. How do they solve what the mesentary evolved to do?
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Is the primitive streak homologous with the archenteron?

Embryogenesis follows different stages across the animal phyla, monoblasts, diploblasts, triploblasts, chordates, and I have a hard time wrapping my head around exactly where they all relate in terms ...
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When does the myotendinous junction and tendon to bone attachments form?

I am a student, and I have been studying tendon development as a part of my curriculum. I have studied about the differentiation of syndetome, and read some articles on tendon development online. To ...
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Evolutionary relationship between liver and spleen?

based on bilateral symmetry, and how embryonic programs work (simple patterns initially, then specialization), for example somitomeres, do the liver and the spleen, that bilaterally occupy the same ...
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What fraction of embryos fail to be born? And why that high?

In the book Developmental Biology by Scott F. Gilbert and Michael J. Barresi, it says: Most human embryos die before being born. You survived. So how come is that true??? And what percentage of ...
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When does the vertebral column finish chondrifying and begin to ossify?

I have read many articles on vertebral column development in embryos on the internet. Different articles give different time periods for the end of chondrification of the vertebral column and the ...
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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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Primitive streak being only present in caudal half of embryo affecting gastrulation?

It is my understanding that in gastrulation epiblast cells migrate to the primitive streak where they start to form the three germ layers; does this mean that gastrulation only occurs at the caudal ...
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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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Schizocoely and Enterocoely [closed]

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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Embryonic cells, when can you detect them in vivo? (In order to do whole genome sequencing)

I was wondering, when is it possible to extract cells (humans or mice) in order to sequence them and detect diseases. Extra: Urine of the embryo in humans is excreted in the 16th week, so I guess that ...
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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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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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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 late in a human pregnancy can a zygote split?

This page indicates that the first two days is "very early" for a zygote to split, and that conjoined twins are the result of an "extremely late" split: If the zygote splits very early (in the ...
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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 we ...
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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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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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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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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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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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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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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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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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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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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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Is the blastocyst a coeloblastula?

A coeloblastula is that type of blastula which has a fluid-filled cavity. Since the blastocyst of mammals has a fluid-filled cavity too, can it be called a coeloblastula? My book however mentions the ...