Microscopy

What are the 3 different cells called?

- Absorptive enterocytes (the four cells with nuclei closer to the apical surface are called absorptive enterocytes.) - brush cells (The two mitochondria rich cells with longer microvilli and nuclei closer to the basal membrane are brush cells) - goblet cells (The dark cell on the bottom of the screen is a goblet cell)

Additional: What two layers are the smooth muscle cells arranged in?

- Outer - the longitudinal smooth muscle cells. are facing towards you, so you can see them as dots - Inner - the circular smooth muscle. Because of their orientation, we can see the whole length of the cells.

What are the tight junctions?

- Outermost junctions are the tight junctions that keep the epithelium sealed

What are the adheres junctions?

- The adherents junctions are usually a bit more basal - Adheres junctions are interconnecting the actin cytoskeleton of the epithelial cells

What are the decompress junctions?

- The decompress are found along the whole inter membrane space. - They connect the keratin cytoskeleton of the cells - Act as anchors that give the epithelium the ability to withstand shearing forces.

The retro viruses accumulate around lymphocytes

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Additional: In healthy individuals, there are approximately ___ lymphocytes per __ epithelial cells.

10 lymphocytes; 100 epithelial cells

Additional: how many nanometers is the best resolution achieved with using a light microscope?

200 nanometers

What type of epithelium is present in the small intestine?

Simple columnar epithelium

The ____ builds an important barrier against pathogens, but it has to absorb ___ efficiently at the same time.

small intestine; nutrients

Even with the highest possible magnification of the light microscope, we can only see a blurry edge of the epithelial cells and cannot resolve the individual microvilli. It's not possible to achieve a higher resolution in the light microscope because:

the wavelength of visible light is too long

The surface of the small intestine is enlarged on many levels. Here you can see the villi. What is the difference between villi and microvilli? (don't confuse)

villi are structures consisting of many specialized cells. Microvilli are the tiny cell extensions on the apical surface of epithelial cells.

Which of the following chemicals was NOT used to stain this tissue?

Eosin to stain eosinophilic structures in various shades of red, pink, and orange

What does the light red layer between the white lumen and blue lamina propria consist of?

Epithelial cells - their main function is to transport nutrients from the lumen into the lamina propria

What is the analine blue stained structure in the sample?

Extracellular tissue - Analine blue binds to extracellular structures such as the fibers in the lamina propria

When do we use a fluorescence microscope?

If we want to take images with a high contrast

Why do we have to start from the lowest magnification to examine a new slide?

It is easier to focus on the specimen

What structure seals the space between two cells and makes it impermeable?

Tight junctions

What is the function of the epithelium?

All - building an impermeable barrier for food-burned pathogens - take up nutrients by passive and active transportation - build a barrier that only allows certain substances to pass through

What is the connective tissue and extracellular matrix composed on?

All - collagen, polysaccharides, proteoglycans ..... + connective tissues such as the lamina propria, mainly consist of the extracellular matrix. (Extracellular means outside the cells)

How could we build a microscope with a higher resolution?

All - use electromagnetic waves with shorter wave - engrossed than visible light and use a sensor to produce a picture - electrons also have wave-like properties - we can use magnets instead of lenses and bombard the sample with electrons instead of light - we could drag a tiny needle over the surface of our sample and record the position of the needle to record the surface structure

Lower the lab pad to count the number of lymphocytes relative to the other epithelial cells. Is there an increased number of lymphocytes in the epithelium?

No, the percentage of lymphocytes does not exceed 10%

What are the oval shaped structures that can be found all over the slide?

Nuclei - the fuchsia stains nuclei bright red b/c it binds to nuclei acids such as DNA and RNA.

Try to identify the basal side facing towards the lamina propria and the apical side bordering the lumen. Which is correct?

The basal side is facing towards the left side of the screen

Additional: What allows us to identify lymphocytes in the epithelium?

The distribution of nuclei allows us to identify lymphocytes in the epithelium

Which statement is true about the fluorescent microscope?

The filter cubes consist of an excitation filter, dichroic mirror and emission filter

Who is the microscopy slide shining with a blue light?

The green fluorescent dye attached phalloidin is excited by blue light and emits green light

Which of the following is not true for DAPI staining?

The light source only emits UV light

What can you conclude from the distribution of the red fluorescence?

The virus seems to accumulate in certain areas

What are the macroscopic structures, which point into the white-colored lumen, called?

Villi - the villi extended into the lumen of the small intestine like the waving tentacles of an anemone. - The villi enlarge the surface area of the small intestine by approx 50x. - The enlarged surface allows more efficient nutrient uptake