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

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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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24 views

Confusion on SAT Subject Test Question

About Question 20, Do cells form 3 poles?
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90 views

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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36 views

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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99 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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1answer
33 views

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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347 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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30 views

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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1answer
86 views

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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2answers
38 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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106 views

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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222 views

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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22 views

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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63 views

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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1answer
674 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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1answer
27 views

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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1answer
95 views

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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1answer
62 views

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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0answers
10 views

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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2answers
60 views

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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1answer
136 views

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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1answer
45 views

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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46 views

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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214 views

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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1answer
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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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67 views

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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62 views

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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210 views

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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169 views

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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1answer
657 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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1answer
1k views

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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0answers
49 views

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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30 views

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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1answer
306 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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2answers
1k views

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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27 views

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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1answer
642 views

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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1answer
2k views

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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1answer
872 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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1answer
103 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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3answers
11k 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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1answer
204 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?
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157 views

Is the amount of blood same in the pulmonary and systemic foetal circulation?

We learn that the stroke volume is the same for the right and left side of the heart. So the amount of blood in either circulations should also be the same. (is it? I myself doubt this statement. As ...
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1answer
136 views

How only one follicle develops into graffian follicle?

I've studied that one out of many follicle develops into mature or graffian follicle. The fact which confuses me is that, since all follicles are in same ovary, close to each other with equal supply ...
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1answer
111 views

Is the thecal sac ectoderm?

The thecal sac, or dural sac, is the membranous sheath of dura mater that surrounds the spinal cord and the cauda equina. The thecal sac contains the cerebrospinal fluid in which the spinal cord '...
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1answer
91 views

Conjoined twins formation theory

is it theoretically possible to take two fertilized mammalian eggs and push them together to make conjoined twins? How about forming non-identical conjoined twins?
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651 views

What tools are used in animal cloning?

So I was reading up on articles to do a project about cloning but there were no places in the article where It states the tool used to take the gene out of the nucleus and insert it into plasmids ? ...
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590 views

Polar bodies fertilization

Suppose a sperm fertilized a 2nd polar body( haploid) is there a chance of somewhat normal development?