Questions tagged [development]

The process through which a biological organism grows to maturity. In certain contexts it can mean the changes the organism goes through over its entire lifetime.

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1answer
45 views

Germ cells vs. gametes

Naively, I thought that germ cells are diploid (in diploid species like human/mouse at least). Then, germ cells undergo meiosis and become haploid. I thought this was the critical change that defined ...
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Do babies have a fight or flight response?

Do babies react in the same way as young children and adults in regards to the fight or flight response? If they do not respond in a similar way or don't have a fight or flight response at all then at ...
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Can the human eye axial length decrease?

I just have a quick question regarding the axial length of the eyeball. I understand that the axial length of the eyeball grows up until your around 20 years of age which is why hypermetropia ...
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26 views

What is the difference between floral primordia and floral buds?

As we know an axillary bud differentiates to form a floral bud, but what is a floral primodium?
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55 views

Can hand sanitizer kill a fertilized human egg cell?

If you took a human egg cell that was fertilized in vitro and sprayed some hand sanitizer on it would it die?
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Does Morphogen acts on morphing surfaces?

I have read lot of examples where at early stages of the development, morphogen gradient gives positional information and causes cell differentiation. But I am wondering if there is a example where ...
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Are there any known consequences of the right-handedness of the DNA double helix?

In this article it is suggested (without evidence) that the right-handedness of DNA may be the cause that "kick[s] off asymmetry in the early embryo [of snails]". On the one hand we know that ...
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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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92 views

Why does it take so long for the human brain to develop from an evolutionary point of view?

I have read that it takes about 25 years for the brain to be fully developed. Coincidentally, humans from the Neolithic and Bronze Age had a very short life expectancy, in fact most of their life ...
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What's the function of vitelline circulation in human embryo?

Why do we need a vitelline circulation if we already develop a placenta to gather all the nutrients we need? Is it an evolutionary remain?
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How much blood do we have when the heart first starts to beat?

How much blood do we have when the heart beats for the first time? It should be between the third and fourth week of embryonic life.
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Reflex muscular activity in three months old fetus

At the end of the third month, reflex activity can be evoked in aborted fetuses, indicating muscular activity This quote is from Langman's Medical Embriology. Have I misunderstood it or it is ...
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What is Balbiani's vitelline body function?

I tried searching on Google Scholar but I found little to no information about this Balbiani's vitelline body. I don't even know why it is called vitelline...I've been taught that it can be seen ...
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67 views

Do any non-human species have juveniles that cannot communicate with adults?

Human babies take 1+ years to begin learning how to speak (though sign language can be learned a bit earlier1). I know that cries, yells, and other non-linguistic sound are a simple form of ...
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130 views

How many times have the cells in a human body divided?

Every single cell in a multicellular organism can in principle trace its "ancestry" back to the zygote through a continuous chain of cell divisions. How many divisions have occurred in a typical cell ...
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How do schistosomes find and attach to human skin?

Schistosomes are parasitic flatworms that have a snail intermediate host and a human definitive host. After developing in the snail, they (cercariae stage) escape into the water and can attach to the ...
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32 views

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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How does X chromosome monosomy occur

I want to understand how Turner syndrome - monosomy X - occurs at the molecular level. The NIH mentions that there are cases of both complete monosomy and of mosaicism. I’m particularly interested ...
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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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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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Does natural selection select for randomness in development?

In a podcast with Sean Carroll and Liv Boeree they discuss a result from game theory that the optimal strategy in the face of incomplete information can require random decision making. For example, ...
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67 views

Why don't rates of cancer increase generation to generation?

As cells divide, they accumulate mutations that can sometimes cause cancer. Gametes have to divide like any other cell, and thus generation to generation mutations should accumulate in people's ...
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How can the same transcription factor be both an activator and suppressor of the same gene?

For example, hunchback in moderate concentrations is an activator of kruppel, but a suppressor of kruppel in large concentrations. From what I've seen in literature, that's because the kruppel's ...
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Technical reason that specialized embryonic cells form

During the embryonic stage of human development, rapid cell division occurs and specialized cells form to build the various parts of the developing fetus. I'm curious: Why technically do specialized ...
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Is there a mechanism of timing or delaying the expression of gap genes?

Summary Gap genes are expressed in presence of the right combination and amount of transcription factors. But is there any additional mechanism of timing the expression of the gap genes to ensure ...
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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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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, a baby starts to hear sounds at week 18. And according to How hearing works. Hearing involves ...
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Is there any example of genetic mechanism of delayed onset toxic effects?

We know that exposure to many toxic chemicals during embryonic development may show toxic effects later in life. It is called Developmental Origins of Health and Disease (DOHAD). Most of the ...
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How is the timing of gene expression controlled in developing embryo? [closed]

I understand how cell differentiation works in general (gradients of homeobox proteins etc), but how is timing controlled? Why do some genes switch on at a very specific moment of development and then ...
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How Does the Body Know a Finger is Fully developed? [closed]

When a baby is being developed inside the womb, 1) how does the baby's body know a finger, or any other part of the body, has been fully developed? 2) following question, how does it "stop" the ...
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67 views

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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108 views

Learning tensors for evolutionary or developmental biology

I'm looking for book recommendations on tensor algebra for use in biology. Tensors are being used increasingly in evolutionary biology and developmental biology, it seems. For example, here is an ...
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98 views

Daphnis Nerii not moving

Its been quite a while since my Daphnis Nerii has passed its eating phase, now its just a sort of recluse and is curled up in one corner and sleeps the whole day. It's a bit brownish in colour now. ...
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212 views

Difference between morphogens and evocators in development?

I am specifically interested in this within the context of 1950's developmental biology (I presume the meaning and scope of usage of the terms has changed since then), as I am reading Alan Turing's ...
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1answer
126 views

Why can a zygote develop into all different types of cell, whereas a differentiated cell cannot? [closed]

A cell formed by the fertilization between two gametes has all the DNA and can lead the development of a human person (or other animals in other species). But other cells in a human person has also ...
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What animal has the longest juvenile period?

I just heard the following complaint from a comedienne. Humans are the only animal that is completely useless for the first twenty five years of life. Obviously this is just a joke but it is true ...
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Role of processing bodies in mammalian development

I am currently writing a project proposal for university admissions regarding the duration till which maternal mRNA is required for mammalian development. Till now all the literature I have read has ...
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520 views

Why does a frog's oxygen intake through the skin and lungs vary throughout the year?

Why does a frogs oxygen intake through the skin and lungs vary throughout the year? And why does the intake through the skin vary slightly while through the lungs dramatically? (Blue line = oxygen ...
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77 views

Text or source (preferably free) for learning developmental biology

I might have to take a graduate level course in developmental biology, of which I have never taken a course in before. The course website lists no recommended texts. Therefore, I assume we will be ...
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49 views

Decision-making in tree limb growth?

Sorry if this is a naive question, but it occurred to me as I was walking across campus today; How does a tree decide which limb is allocated the most resources, and thus grows the largest? My first ...
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835 views

Humans have tails? [duplicate]

Today in biology class, my teacher said that all chordates have all the necessary traits, at least during the embryo stage, and we humans are chordates. So, one of these necessary traits was that they ...
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69 views

What happens to the language processing brain part if no language is ever learned?

Language is processed in the human brain in multiple regions. Some of them seem to be used exclusively or mainly for language processing, other regions are distributed overlapping with other functions....
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Is an animal's body height dependent on its environment?

Imagine the follwing situation: a newly born animal is brought into a small room. This room has no windows, but artifical light to imitate the sunlight. Furthermore, this light behaves like the sun, ...
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Are male and female brains physically different from birth?

Male and female brains are wired differently according to this article: Maps of neural circuitry showed that on average women's brains were highly connected across the left and right hemispheres, ...
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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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What is the real meaning of the statement “*ontogeny recapitulates phylogeny*”? [closed]

I tried searching in this site but couldn't find an appropriate answer to the title question: what is the real meaning of the statement "ontogeny recapitulates phylogeny"?

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