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

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Why is polyploidy lethal for some organisms while for others is not?

Polyploidy is the multiplication of number of chromosomal sets from 2n to 3n (triploidy), 4n (tetraploidy) and so on. It is quite common in plants, for example many crops like wheat or Brassica forms. ...
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Impact of Alan Turing's approach to morphogenesis

Shortly before his untimely passing, the computing pioneer Alan Turing published his most cited paper The Chemical Basis of Morphogenesis (1952). The central question for Turing was: how does a ...
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343 views

Why do pandas have a high probability of giving birth to twins?

According to the BBC documentary "Wild About Pandas", about half of panda birth result in twins. Why do they have such a high probability compared to other mammals? What factor(s) control that ...
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613 views

Could a fetus properly develop in micro/zero-gravity?

I suppose another way of looking at the question is: how important is gravity for the development of mammal fetuses? And if things would go wrong, what sort of things would they be, and what would be ...
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What determines testosterone exposure in womb, baby's genetics or mom's body?

I read this article which has the following quote: The ratio between index and ring finger is believed to be linked to exposure to the male hormone testosterone in the womb. And I wonder what ...
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318 views

Do twins “run in the family”?

My wife and I recently found out that we are going to have twins and so nearly everyone asks if we have a family history of twins. Now I know that the answer for me is that it doesn't matter—as ...
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212 views

evolutionary reason behind sharing the same path for food and air?

What is the evolutionary reason behind sharing the same path for food and air? For example, we have a nose and lungs, yet they are linked by the pharynx, which is shared with the mouth and ...
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398 views

Do birds have navels?

This picture shows the development inside a bird egg: This shows the connection of the embryo to the yolk sac. Does this mean birds have navels? And if so, what happens to the umbilical cord once ...
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How are babies born without a brain?

In the United States, anencephaly occurs in about 1 out of every 10,000 births. There are several forms of this condition, wherein the forebrain is absent. The forebrain is host to most of the higher ...
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570 views

What forms the human amniotic sac?

I am trying to understand the formation of embryonic disc for human and chick so the following question is related to here about formation of embryonic disc. I had thought that the amniotic sac forms ...
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56 views

Is telomere shortening consistant over consecutive cell divisions from zygote to a differentiated cell?

Considering the complexity of embryogenesis, a temporal referance would be helpful to coordinate the developmental sequences during embryogenesis and fetal development which is to be completed within ...
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What is the total number of rounds of cleavage during mammalian embryonic development?

That for frog is 12, but what about mammalian embryos? I cannot find the exact number anywhere.
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Does our eyeball increase in size as we grow?

Does the size of the eye increase as we develop from the stage the complete eye first forms to infancy and then to adulthood ?
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There are linear and rotary molecular motors in the cells. Do any of them have a fixed or stable frequency or speed?

Are there any linear, rotary or oscillatory molecular motors in the cells which can have fixed frequeny and which can be used as a reference for elapsed time timer? This question is with relevence to ...
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453 views

What metabolic activities are performed by a developing human fetus's liver?

I understand that organ function varies with the stages of development. Does a fetal liver EVER perform lipogenesis, gluconeogenesis, make bile, etc? Or does it only begin performing these actions ...
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1answer
174 views

When does Coelom form exactly?

Related to my other question. I know that the coelom is derived from mesoderm. Coelom seems to form during organogenesis within 3rd and 8th week of embryogenesis. However, that answer is not either ...
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65 views

How compatible are mammal wombs?

I had read about science working towards the creation of artificial wombs however I wonder how compatible are mammal wombs and connected systems to develop fetuses. What species are so compatible that ...
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Fetal development, gastrulation and embryonic disc

I am completely confused by the images circulating on the internet of human gastrulation. First, lets see how it happens in deuterostomes. This image depicts the process: (image is from Wikipedia) ...
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Cytoplasmic determinants - protostomes and deuterostomes

Cytoplasmic determinants are spread unevenly in the egg, and so when embryo starts forming (cells start dividing), the determinants are also unequally divided between cell. This unequal distribution ...
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1answer
370 views

Causes of monozygotic twins

Twins could be monzygotic i.e. identical twins and dizygotic i.e. non-identical twins.Well, monozygotic twins occur when a single egg is fertilized to form a zygote which later divide into separate ...
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298 views

Why are eggs “egg” shaped?

Is there a reason as to why chickens lay "egg" shaped eggs, as opposed to spherically shaped eggs (or a random shape)? <--- Main Question For extra points (actually just to add more words in ...
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Do humans have Coelom?

Kimball Biology 5e says Coelom is the main body cavity of many animals. It is lined with an epithelium derived from mesoderm. Gilbert Embryonal Biology 9e says Coelom is the space between ...
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What are differences between formation of embryonic disc in chick and mammal embryo?

Exam question which got lowest average points in my university: 1/5 average. No markscheme available so my attempt below. I assume that embryonic disk prefers to germ disk such that Formation prefers ...
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236 views

which exact mechanism triggers the first cell differentiation after n divisions?

I would like to understand which mechanism triggers the first cell differentiation after n divisions. I read previous articles on SE and Wikipedia articles on cellular differentiation and ...
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1answer
279 views

Does chicken embryo form the disc called “discoblast” in the cleavage and blastulation of chicken?

This thread is related to my previous thread which is still unsolved mainly. I need to be able to compare chick and human cleavage and blastulation of zygote. My friend says that Chicken have ...
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84 views

Activation Of Embryonic Genome

Embryonic gene activation is a process by which the embryo begins to transcribe its newly formed genome.As the embryonic gene activation occurs during early stages the paternal genome may not have any ...
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264 views

Where does meiosis II of oogenesis end exactly in tuba uterina - uterus?

I know that metaphase II ends at ampulla tuba uterina, but I am not completely sure where the telophase II ends. Is it in the triangular section of cervix uterii? I just have an intuition that the ...
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99 views

Which process is needed to complete male reproductive development?

In order to properly complete male reproductive development: ...
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55 views

If two definitive ovums are fused will they form an organism?

Pretend that somehow in a laboratory two definitive ovums (finished 2nd miotic divisions) are are fused together. Will they form a new species?
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29 views

How many areas are there in Brodmann map?

I read Wikipedia claiming 52. I heard that this can be extended to 54. I see there is no limit of having more areas - just better understanding of the neuroblast migration and fibroblast too, ...
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Simulating Cell differentiation

I'm a computer programmer deeply interested in Biology. I wish to write a computer simulation for cell differentiation. I understand there will be seemingly impossible challenges in doing this. But ...
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1answer
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Development of vitreous humor

I have tried reading about development of vitreous humor but it is all very confusing. When does it first developed ? Does it renew itself ? Please provide reliable sources..
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Roles of creatine and bilirubin in foetus circulation

I think they are not inputs from maternal placenta. I think they are the results of foetus metabolism. However, I do not understand it how and where exactly. What are the roles of creatine and ...
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1answer
374 views

How many consecutive cell divisions are required to form the adult human body from the single cell zygote?

The preferred question would have been what is the total number of cells in a full term human foetus and how many cell divisions are required to reach that number. However estimates of total cell ...
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70 views

How does an embryo know where to grow limbs etc

For example you have a cell or already a bunch of cells. Those cell(s) divide and after several week you have a grown organism, for example a human with limbs, several different organs etc. However, ...
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142 views

Why are Birds and Reptiles with abundant yolk sac polyspermic?

I was given an explanation that birds and reptiles are polyspermic because they have an abundant yolk sac. But how does it explain the thing? Chicken as an adult is not using in my opinion yolk as an ...
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Limb polarity such as writing handedness, golf handedness and natural football foot

Define the term "limb polarity" to mean things such as writing handedness, golf handedness, throwing ball arm preference and natural boxing hand. I avoid using the term "handedness" because of its ...
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41 views

Which part of the genome are the developmental sequences of embryogenesis located?

Which part or parts of the the genome are the sequences located. Are they spread across the chromosomes? If so how are they accessed sequentially with precision during embrygenesis?
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62 views

Which X-Y chromosomes have the developmental genes for mammals?

I know that for a given mammal, half the chromosomes come from father and half from mother. This is typically denoted as x-y. I've recently read about "toolkit" genes that control how a cell develops ...
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1answer
46 views

Waste generation by embryo [closed]

How does an embryo produce waste products even when its organ systems are not developed fully ? How does the placenta identify or differentiate waste materials from embryo ? Which organelle or ...
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51 views

Is there any bank of animations for Embryology?

I am trying to find animations which can anonymous or generalised for Embryology. However, I have not find any single good source. Is there any bank of animations for generalised embryos?
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108 views

What's the difference between an embryo and a fetus?

The most I've been able to come up with is that fetuses are embryos slightly farther along in their development. Is that correct? Thanks! evamvid
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120 views

Why is the threshold between human embryo and human fetus defined as 8 weeks after fertilization?

Why is the threshold between human embryo and human fetus defined as 8 weeks after fertilization? What's happening on the 8th week? Note: definition of embryo based on Wikipedia's current ...
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1answer
12 views

Function and process of TCTE-1 receptor

I was wondering if anybody knew of the function and process of the TCTE-1 receptor during the binding of a sperm with an egg. The only think I know of TCTE-1 is that it is a species-specific receptor. ...
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1answer
26 views

Significance of prostaglandins in semen?

I am trying to figure out how prostaglandins in the semen relate to the female reproductive tract. More specifically, How does prostaglandins in semen help the female reproductive tract increase the ...
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37 views

Regulation of the replication of mtDNA at embryonic level

While reading an article on mitochondrial inheritance I came across this link. The results state that mitochondrial DNA replication is regulated in different cells of an embryo at different levels. ...
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1answer
60 views

What is a zygote?

During fertilization, the nuclear membrane of the pro-nucleus of the ovum and sperm degenerate. Is the cell is stage called a zygote? After the dissolution, mitosis occurs and two cells are formed.Or ...
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1answer
47 views

Mutated Sperm - What happens?

I saw on TV that not all sperm are the same. Some have mutations like 2 and 3 tails? There were other mutations as well. If one of these mutated sperm actually fertilized an egg, would the embryo ...
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30 views

Purpose of certain genes in embryonic development [closed]

(Please correct me if I'm wrong on any count here). As I understand it, development requires the action of numerous genes and proteins. My textbook has described it as being almost reminiscent of a ...
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13 views

Cytoplasmic determinants in amphibians

If cytoplasmic determinants are distributed before fertilisation then how can an amphibian's embryo, whose dorsal side is determined after fertilisation develop ?