The right option is; dark-field microscope
A light microscope that makes the specimen appear light on a dark background is called a dark field microscope.
Dark field microscopes are light microscopes that are used in different ways to clearly view various specimens that are unstained, transparent, and hard to see using a light field unit. Dark field microscopes are very effective because they show the details of unstained and live samples. It is also very simple to use, and inexpensive to set up.
Astrocytes are a group of cells with functional characteristics and distinctive morphological that vary within specific areas of the brain.
For healthy brain function, astrocytes are essential. those become reactive in the case of Alzheimer's disease, which impacts the signaling properties. while experimenting, there was the measurement for instinctive calcium transients ex vivo in hippocampal astrocytes in brain slices containing the dentate gyrus of 9-month-old and 6-month-old APPswe/PSEN1dE9 mice. when they investigated the duration of calcium transients and frequency concerning amyloid-β (Aβ) pathology, the proximity of the astrocyte to Aβ plaques, and aging. there was no change in spontaneous calcium-transient properties of 6M APP/PS1 astrocytes compared to wild-type astrocytes, whereas there was hyperactivity in 9M APP/PS1 astrocytes compared to wild -type, which were longer in duration, also there was an effect of aging too, there was an increase in calcium in the 9-month astrocytes than to the 6-month astrocytes, also there was an increase in the calcium waves in the 9-month astrocytes because of the increase network activity. The findings were that the change in calcium signaling in individual astrocytes of APP/PS1 mice is because of both pathology and aging but these don't have any impact on changes in the astrocyte network activity, which leads to helping to understand changes in neuronal physiology.
To know more about neuronal physiology refer to the link brainly.com/question/17060419?referrer=searchResults.
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2. Why are biologist concerned about because system disruption?
