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What is 'refractile' cell morphology?

What is 'refractile' cell morphology?


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I can't find a definition for 'refractile' (not 'refractory', and not explicitly in an optical context).

As in:

A tumour cell phenotype features increased proliferation, anchorage- and growth factor-independenth growth and 'refractile' cell morphology

It's not in any of the dictionaries I can access online, nor in the Oxford Dictionary of Biochemistry and Molecular Biology. Any help would be appreciated, thanks.


From the Biology Online Dictionary, refractile refers to:

… the ability of cellular granules to refract or scatter light.

Tumor cells can be more "dense", as they are usually rapidly dividing, and so need extra ribosomes to maintain protein production, may have a higher DNA/RNA content reflecting increased transcription and duplication, more mitochondria to power the cells, etc. This can alter the refractive index of a suspension of tumor cells as compared to organ-matched normal cells, for example.


Please note that this explanation may not be the actual physics definition, but it will help you to understand the concept of 'refractile' cell morphology…

From the statement below by www.brittanica.com it appears that light is both partially reflected by & partially refracted or "transmitted" (think absorbed) into the object it is hitting. (Technically transmission is NOT absorption, but for this purpose it's easier to think of it as being absorbed by the cell/cell parts).

So when light hits the cells/cellular parts in a scan, some of the light is reflected back and some of the light is "absorbed" by the cell/cell parts. The amount of light "absorbed" is variable for each cellular component, and therefore, the amount of light reflected back is also variable.

In the scan or microscope, we actually "see" the reflected light. Not the refracted (absorbed) light and because the light reflected is variable, we are able to "see" the different components of the cell (i.e the different amounts of light reflected by the various parts).

So the statement 'refractile' cell morphology means that the cell has components which absorbs light at variable amounts and therefore, also reflects light at different amounts. Essentially, you are able to "see" the cell morphology & its differences because it refracts (absorbs) some light and reflects the rest.

Hope this helps get the concept. =)

"When a ray of light is incident upon a plane surface separating two mediums (e.g., air and glass), it is partly reflected (thrown back into the original medium) and partly refracted (transmitted into the other medium)." https://www.britannica.com/science/radiation/The-structure-and-properties-of-matter#ref398785


Microbiology – Morphology of Bacterial cell

Morphology means systematic study of external characters of bacteria.

Morphology of bacterial cell deals with study of

1. Size of bacteria.

  • Size of bacterial cell is less than 3 micrometer.
  • The bacteria are microscopic in nature and are visible only under compound microscope.
  • These bacteria may be spherical,cylindrical or spiral in shape.
  • Size of a spherical shape bacteria can be measures in diameter.
  • Size of a cylindrical bacteria is measured by its length and width.
  • In spiral shape bacteria length is measured but due to spiral form it is not exact.
  • As we know all bacteria are microscopic in nature so their size is also measured under microscope.
  • Size of bacteria is measured by using calibrated slide and calibrated occular compound microscope is used.
  • The above method of measuring size is called as micrometry.
  • The size of bacteria can also be measured by electron microscopic micrometry.
  • Units of measurement used in bacteriology are
  1. Micron or micrometer.
  2. Nanometer (nm) or Millimicron.
  3. Angstrom (A°)
  • The conversion are as follows
  • 1 μm = 10 -3 mm = 10 -4 cm = 10 -6 meter1 nm = 10 -3 μm = 10 -6 mm1 A 0 = 10 -1 nm = 10 -4 m =10 -7 mm
  • Size of spherical bacteria or cocci ranges from 0.5 to 3.0 μm.
  • Size of cylindrical or rod shape bacteria ranges from 0.15 μm to 2.0 μm in width and 0.5 μ to 20 μ in lenght.
  • The small size of bacteria have large surface area for entry of nutrients, water and exit of waste.

2. Shape of bacteria

  • Shape of bacteria cell depends on the rigidity of cell wall.
  • There are three shapes of bacteria.

a) Spherical or cocci shape.

If the cells are spherical or ball shape then the cells are called as cocci or spherical shape bacteria.

b) Cylindrical or rod shape.

If the cells are rod or cylindrical in shape it is called bacilli.

c) Spiral shape.

A bacteria which is twisted two or more time along the axis is called a spiral form bacteria.

3. Arrangement of bacterial cells.

Variety of arrangement of cells is observed in cocci and rod shape bacteria.

a) Arrangement of cocci cells.

  • Singly :- If a cocci cell appear individually then simply it is called cocci.
  • Diplococci :- When two cells are attach to each other even after dividing them in one plane is called as diplococci.
  • Streptococcus:- If cocci cells are arranged in long chain and remain attach to each other even after dividing them in one plan is called as streptococcus.
  • Staphylococcus:- If the cocci cells arranged in form of a cluster even after dividing them in three plane then these cocci cells are called staphylococcus.

b) Arrangement of rod shape bacteria.

Bacillus cells show very less variety in arrangement of cells as these cells can be divided only in one plane.


Cell Morphology

Regularly examining the morphology of the cells in culture (i.e., their shape and appearance) is essential for successful cell culture experiments. In addition to confirming the healthy status of your cells, inspecting the cells by eye and a microscope each time they are handled will allow you to detect any signs of contamination early on and to contain it before it spreads to other cultures around the laboratory.

Signs of deterioration of cells include granularity around the nucleus, detachment of the cells from the substrate, and cytoplasmic vacuolation. Signs of deterioration may be caused by a variety of reasons, including contamination of the culture, senescence of the cell line, or the presence of toxic substances in the medium, or they may simply imply that the culture needs a medium change. Allowing the deterioration to progress too far will make it irreversible.


Crystalloid body, refractile body and virus-like particles in Apicomplexa: what is in there?

The phylum of Apicomplexa comprises parasitic protozoa that share distinctive features such as the apical complex, the apicoplast, specialized cytoskeletal components and secretory organelles. Other unique cytoplasmic inclusions sharing similar features have been described in some representatives of Apicomplexa, although under different denominations. These are the crystalloid body, present for example in Cryptosporidium, Plasmodium and Cystoisospora the refractile body in Eimeria and Lankesterella and virus-like particles, also present in Eimeria and Cryptosporidium . Yet, the specific role of these cytoplasmic inclusions in the cell cycle of these protozoa is still unknown. Here, we discuss their morphology, possible inter-relatedness and speculate upon their function to bring these organelles back to the attention of the scientific community and promote new interest towards original research on these elusive structures.


Functional Morphology

Functional morphology involves the study of relationships between the structure of an organism and the function of the various parts of an organism. The old adage "form follows function" is a guiding principle of functional morphology. The function of an organ, appendage, tissue, or other body part dictates its form. Furthermore, the function can often be deduced from the form. The idea of relating form and function originated with the French naturalist Georges Cuvier (1769-1832).

The primary task of functional morphology is observing living organisms to see how they live and function. From observations of living organisms, scientists also attempt to discern principles that will allow them to determine function from the forms of fossils, such as bones, shells, or whatever happens to be preserved from organisms that no longer exist. Theoretical morphology tries to determine the limits of form not every conceivable form could actually exist in nature.

Functional morphology studies the ways in which structures such as muscles, tendons, and bones can be used to produce a wide variety of different behaviors, including moving, feeding, fighting, and reproducing. Functional morphology integrates concepts from physiology, evolution, development, anatomy, and the physical sciences, and synthesizes the diverse ways that biological and physical factors interact in the lives of organisms. Functional morphology and biomechanics allow scientists to observe and quantify not only how animal skeletons and joints move and how muscles work but also how these things relate to the diversity of animal behaviors.

Functional morphology helps to understand the form of modern animals. For example, even casual observation reveals that elephants have very thick legs relative to their body size when compared with smaller animals such as antelope or horses. This is not just a fluke of nature's design elephants need thick legs to hold up their body mass. But why are the legs of an elephant proportionately thicker than the legs of smaller animals?

The mass of an object is related to its volume. Imagine an animal, an elk for example, scaled up to be twice as tall (about the height of an elephant) while keeping all proportions the same. An animal twice as tall as another animal of a similar shape will have much more than twice the volume. Because it is also twice as long and twice as wide, the scaled-up elk will have eight times as much volume as the normal-sized elk. Assuming bone and muscle density remain about the same, the scaled-up elk will also have eight times as much mass. However, the legs of the larger elk will only have four times the area of the legs of the normal-sized elk.

According to the principles of engineering, the strength of a column of bone and muscle is proportional to its cross-sectional area. Legs with only four times the cross-sectional area will not be strong enough to hold up eight times the weight. To hold up the scaled-up elk, its legs must be proportionately thicker than the legs of the normal-sized elk. Consequently, in order to attain the great size they have, elephants had to evolve legs proportionately much thicker than those of smaller animals.

Elephants also have large ears. Functional morphology helps to understand this feature as well. As elephants evolved to larger body size, the area of their skin did not increase as rapidly as their volume. Thus, the elephant's skin could not dissipate enough heat to keep the elephant cool. The elephant's relatively large ears, however, significantly increase its ability to give off heat. Forest elephants live in somewhat cooler environments, so their ears are not as large as elephants that spend more time in the sun.

Functional morphology also helps to understand the limits on the size of cells. If a spherical bacterial cell grows to twice its original size, it has eight times the volume but only four times the surface area. Because the cell absorbs nourishment through its surface, it must sustain eight times as much mass with only four times as much nourishment. At some point, a cell will become so large that it cannot absorb enough materials to sustain its mass, and it will then divide.

Elliot Richmond

Bibliography

Curtis, Helena, and N. Sue Barnes. Biology, 5th ed. New York: Worth Publishing, 1989.

Cuvier, Georges. Memoirs on Fossil Elephants and on Reconstruction of the GeneraPalaeotherium and Anoplotherium. New York: Arno Press, 1980.

Gould, Stephen J. The Panda's Thumb. New York: Norton, 1980.

Huxley, Julian S. Problems of Relative Growth. New York: Dial Press, 1932.

Purves, William K., and Gordon H. Orians. Life: The Science of Biology. Sunderland, MA: Sinauer Associates Inc., 1987.

Thompson, D'Arcy W. On Growth and Form. Cambridge: Cambridge University Press, 1942.

Functional Morphology>FUNCTIONAL MORPHOLOGY

A couple walk hand in hand along the beach. Suddenly an ant appears at the top of a sand dune, scaring the wits out of the couple. This is no ordinary ant, this is a giant ant the size of an elephant! Since ants are extremely strong for such small animals, this gigantic ant must be unbelievably strong, able to throw automobiles around like toys, right? Actually, no. As an object increases in size, its weight grows much faster than its strength. When an object doubles in size, it becomes four times as strong, but eight times as heavy. The thin legs of the ant are strong enough to support several times its own weight. However, if the ant were scaled up to be as tall as an elephant, its legs would be too flimsy to hold up its own weight.


Embryology

The structures and the relationships among the various parts of a mature plant or animal are usually better understood if the successive developmental stages are studied. Thus, morphologists have traditionally been interested in the study of embryos and their developmental patterns—i.e., the science of embryology.

Development typically begins in animals with the cleavage, or division, of the fertilized egg (zygote) to form a hollow ball of cells called the blastula the blastula then develops into a hollow cuplike body of two layers of cells, the gastrula, from which the embryo ultimately is formed. At one time, the techniques available to embryologists enabled them to study only whole embryos at different developmental stages. The science of experimental embryology began during the first half of the 20th century, when microsurgical techniques became available either for the removal and study of certain structures from tiny embryos or for their transplantation to other regions of the embryo. Advances in understanding the mechanism by which biological information is transferred in DNA and the means by which this information results in the production of specific proteins have led to efforts to describe development in biochemical terms. Although hypotheses regarding the reasons for the appearance of a specific enzyme or some other protein at a specific time during development have been formulated and tested, the biochemical basis of morphogenesis itself—that is, the reason for the development of particular structures—is not fully understood.

The development of the seed plant is basically different from that of an animal. The egg cell of a seed plant is retained within the enlarged lower part, or ovary, of the seed-bearing organ (pistil) of a flower. Two sperm nuclei pass through a structure called a pollen tube to reach the egg. One sperm nucleus unites with the egg nucleus to form the zygote from which the new plant will develop. The second sperm nucleus unites with two nuclei, called polar nuclei, to form a body called a triploid endosperm, the cells of which divide to form a nutritive mass within the seed. The zygote undergoes several cell divisions to form the embryo, which is surrounded by the endosperm. The embryo develops one or two seed leaves, or cotyledons, which may become thick and fleshy with stored foodstuffs. The epicotyl, which consists of a growing point enclosed by a pair of folded miniature leaves, develops above the point of attachment of the seed leaves. Below the seed leaves extends the hypocotyl, the tip, or radicle, of which forms the primary root of the embryonic plant.

The factors involved in initiating and controlling morphogenesis in plants have been studied by growing cells, tissues, and organs derived from plants. Indeed, an entire carrot plant has been grown from one cell of a mature carrot. This provides striking evidence that the cell from the adult plant contains all of the genetic information needed to produce an entire plant, including roots, stems, and leaves. The technique of growing plants from isolated plant parts has been useful in studies involving the characteristics of embryonic growth, the correlated growth of plant parts, and the nature of differentiation and regeneration (the replacement of lost parts).


Cell Tracing, Tracking, and Morphology

Invitrogen™ Molecular Probes™ fluorescent products provide a unique toolbox for studies of cell proliferation, migration, chemotaxis, and invasion. Labeling strategies range from expressing fluorescent proteins to loading long-lasting probes or cell-permeant cytoplasmic labels to fixable membrane tracers.

These diverse reagent classes can be used for labeling mammalian cells to view changes in morphology and location. Cell tracers are frequently used in dye dilution assays to monitor cell proliferation using flow cytometry. Other trackers and tracers in a wide variety of colors provide efficient and sensitive methods for monitoring specific cells within a population by flow cytometry or imaging, in culture or in whole animals.


Prokaryotic cell Structures that are Visible through Light microscope

The maximum magnification that can be obtained from a light microscopy is 1000x or 1500x and the maximum resolution is 0.2μm. Hence only a very few details can be observed. The use of different staining techniques helps to identify and observe different components of the cells. Cell size and shape can be easily determined with the help of light microscopy.

Size and morphology of bacteria:

Bacterial morphology is very diverse. The two major types of bacteria based on its morphology are:
A) Coccus.
B) Bacillus.

Apart from these shapes, square shaped and rectangular shaped bacteria are also found. Some bacteria are found in a variety of shapes and lack a single, characteristic form. These are called pleomorphic.

Cocci are roughly spherical cells. They may exist as individual cells or are clustered together. In some cases as in the genus Neisseria the cells may be found in pairs. Such a pair of Cocci is known as diplococci.

Sometimes they may be found attached to each other as in chains. This type of morphology is shown by genus Streptococcus, Enterococcus and Lactococcus.

In certain genus like Staphylococcus the cells are clustered together like grapes.

Bacilli are rod shaped bacteria. Various bacilli may vary in length to width ratio. There are certain bacteria that are so short that they resemble coccus and are termed coccobacilli.

The shape of the rod's end may be flat, cigar-shaped or circular. Some of the bacteria as distinctive curves and are known as vibrios.

Some bacteria are shaped like long rods twisted into spirals or helices are called spirillum.


Types of Nucleic Acid

Unlike nearly all living organisms that use DNA as their genetic material, viruses may use either DNA or RNA as theirs. The virus core contains the genome or total genetic content of the virus. Viral genomes tend to be small, containing only those genes that encode proteins that the virus cannot get from the host cell. This genetic material may be single- or double-stranded. It may also be linear or circular.

DNA viruses cause human diseases, such as chickenpox, hepatitis B, and some venereal diseases, like herpes and genital warts. Human diseases caused by RNA viruses include hepatitis C, measles, and rabies.


Types of Nucleic Acid

Unlike nearly all living organisms that use DNA as their genetic material, viruses may use either DNA or RNA. The virus core contains the genome or total genetic content of the virus. Viral genomes tend to be small, containing only those genes that encode proteins that the virus cannot obtain from the host cell. This genetic material may be single- or double-stranded. It may also be linear or circular. While most viruses contain a single nucleic acid, others have genomes that have several, called segments.

In DNA viruses, the viral DNA directs the host cell&rsquos replication proteins to synthesize new copies of the viral genome and to transcribe and translate that genome into viral proteins. DNA viruses cause human diseases, such as chickenpox, hepatitis B, and some venereal diseases, like herpes and genital warts.

RNA viruses contain only RNA as their genetic material. To replicate their genomes in the host cell, the RNA viruses encode enzymes that can replicate RNA into DNA, which cannot be done by the host cell. These RNA polymerase enzymes are more likely to make copying errors than DNA polymerases and, therefore, often make mistakes during transcription. For this reason, mutations in RNA viruses occur more frequently than in DNA viruses. This causes them to change and adapt more rapidly to their host. Human diseases caused by RNA viruses include hepatitis C, measles, and rabies.


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