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7 votes
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What does lymph actually look like?

This seems to be one of rare actual photos of lymph online (suggested in the comment above): Image: Lymph (source: IJCRI - Case Reports Journal)‎ This particular lymph (or "lymph fluid" or "...
Jan's user avatar
  • 8,089
6 votes
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What are the roundish objects in this sketch of a tracheid?

The 'roundish stuffs' you are seeing are called 'pits'. The Dictionary of Botany defines a pit as '[a] cavity in the secondary cell wall, allowing exchange of substances between adjacent cells'. The ...
Epistemonaut's user avatar
6 votes
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Is there a surface or body cavity that does not have epithelium?

Short answer Edit with credits to anongoodnurse: As far as I know, every bodily surface and cavity is covered by epithelia. Background Epithelial tissue is a sheet of cells that covers a body surface ...
AliceD's user avatar
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6 votes
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If cells regularly renew, why do we have scars?

Scar tissue formation is part of the normal healing process in which fibrous material braces and pulls the wound together, in other organisms (and young mammals) this process is mild and just serves ...
John's user avatar
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6 votes
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What is the cell matrix?

The quote (which you more likely got from Wikipedia) discusses multiple types of matrices. Let's break down the quoted definition: The general definition of a matrix would be "an environment or ...
theforestecologist's user avatar
6 votes
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How can soft tissue exist in dinosaur fossils?

keratin and collagen are an incredibly tough molecules so if it is isolated from the environment (oxygen and bacteria) it could easily survive for that long. Not all proteins are equal some are very ...
John's user avatar
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4 votes
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Which organs/tissues are defined as "peripheral organs/tissues"

The most common usage of "central" vs "peripheral" organs/tissues is: central nervous system (brain/spinal cord) vs all other organs/tissues: "B cells in peripheral organs and the CNS" (from the ...
Jan's user avatar
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3 votes
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Is it possible to determine what tissue a DNA sample came from based solely on its sequence?

The answer is in the question but I suppose you wanted to ensure you were not missing some info. Answer The DNA sequence is the same in all cells of a multicellular organism. Only the expression ...
Remi.b's user avatar
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3 votes
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White blood cells after dealing with an infection

White blood cells, especially neutrophils, rapidly leave the blood and migrate in tissues toward infections (or other forms of stimulations). Many of them do die at the location of an infection, but ...
iayork's user avatar
  • 14.3k
3 votes

Do "scars" in humans replace all the skin layers or only some layers?

This depends on how deep was the initial wound, and how that wound healed. There are mainly two ways a wound could heal, either by primary intention (like in surgically closed wounds), or by secondary ...
Matt Dee's user avatar
  • 189
3 votes

Is collagen supplementation useless?

Regarding the use of collagen supplements to help prevent or treat a tendinopathy: A rather inconclusive quote from a 2016 systematic review {1}: glucosamine and chondroitin sulphate, vitamin C, ...
Franck Dernoncourt's user avatar
3 votes

How do trees grow?

You will find the nail at the same height. Trees grow by a) adding to the tips of their branches (sometimes sprouting new branches at nodes), and 2) adding to their diameter. (Only a thin layer ...
jamesqf's user avatar
  • 3,643
2 votes

most different human tissues with respect to gene expression profiling

You can navigate the GTEX project. PCA section. https://www.gtexportal.org/home/histologyPage?tab=PCA You have different samples for many tissues. Currently you can navigate it tissue by tissue but ...
biojl's user avatar
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2 votes
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What do you mean by non cellular matrix

You're looking for the extracellular matrix: In biology, the extracellular matrix (ECM) is a collection of extracellular molecules secreted by cells that provides structural and biochemical support ...
LinuxBlanket's user avatar
  • 1,313
2 votes
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Might new bones evolve from soft tissue?

New bones do form occasionally so it is not impossible, Ornithischian dinosaurs are defined by a evolution of a new bone (predentary). There are many pieces of cartilage in the body that become ...
John's user avatar
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2 votes
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Is pith a ground tissue with no specialized function?

Short answer: it's not the greatest question. Long Answer: So there are three primary tissues in a plant: ground tissue, dermal tissue, and vascular tissue. See below for how they sort out: However,...
theforestecologist's user avatar
2 votes

Why is xylem a tissue and not an organ?

In plants, there are three types of tissue: meristematic, simple, and complex. Meristematic (embryonic and totipotent) Simple (composed of only one type of cell), such as parenchyma collenchyma ...
Sartoaster11's user avatar
2 votes

Parietal and Visceral epithelia

Yes, the parietal pleura is on the wall of the thorax. That picture isn't great. Each lung has its own pleural cavity, ie its own visceral+parietal. Another important thing is the folding over. ...
Ricky's user avatar
  • 87
2 votes
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Why doesn’t heart have smooth muscle tissues?

Striated muscle contraction is synchronized by the structure at the individual fiber level, this also produces a lot more force. They also have a faster recovery time than smooth muscle. Presumably ...
John's user avatar
  • 14.7k
2 votes

What is the proper anatomical name of the "band of Richer" that wraps around the quadriceps femoris?

There is no such ligamentous or connective tissue structure as depicted in the linked image. This is a visual artifact created by the border of the vastus medialis or just a fanciful artistic ...
kmm's user avatar
  • 12.3k
2 votes

Can you have a higher nitrogen load in your tissues after travelling over a hill?

After a lot of discussion with my diving officer, we've agreed that the following might be true. I'm not going to accept this as an answer until I've had some affirming opinions though. The diagrams ...
ScottishTapWater's user avatar
1 vote

Reference for standardized histology rating criteria of microscope images

Consider the 1951 USAF resolution test chart (inline below). It has arrays of progressively smaller spatial frequency features. Just find the smallest feature that can be resolved and use this as a ...
selene flemming's user avatar
1 vote

Name/term for mechanisms by wich the relative size/number of cells of some tissue/organ are preserved

You are referring to organ “scaling” and “allometry”.
J--'s user avatar
  • 428
1 vote

Name/term for mechanisms by wich the relative size/number of cells of some tissue/organ are preserved

'Eutely' is the term used for organisms with a fixed number of somatic cells. I'm not aware of any term for sub-organismic structures.
Quercus Montana's user avatar
1 vote

Could bacteria and phages be found in tissues?

Per my comment to the question, here is an answer to the same question asked on ResearchGate: Whole genome sequencing of human tissue samples often results in reads aligning to bacterial references, ...
acvill's user avatar
  • 8,296
1 vote

Why is cartilage replaced by bones in a vertebrate adult?

Short answer, cartilage can't provide the same support as a bone, bone is stronger and stiffer. Sharks may be big but they have pathetically weak bites for their size and that even when they ...
John's user avatar
  • 14.7k
1 vote

Why is cartilage replaced by bones in a vertebrate adult?

Bones are complex organs, made of more than just a structural element. Cartilage is just a tissue, usually devoid of nerves and blood vessels. Chondrichythes live in water (ἰχθύς ichthys is Greek ...
Mowgli's user avatar
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1 vote
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Is it possible to extract tissue-culture material from a seed?

Yes. It's quite common, to the degree that it's done by some hobbyist plant breeders. See en.wikipedia.org/wiki/Embryo_rescue However, AFAIK (I'm not an expert), it wouldn't be done for raising ...
jamesqf's user avatar
  • 3,643
1 vote
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What are pit fields?

Pit vs plasmodesmata From wikipedia > pit Pits are thin portions of the cell wall that adjacent cells can communicate or exchange fluid through, utilizing plasmodesmata. The definition of "pit" ...
Remi.b's user avatar
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