Swelling microscopic

Fig. 4. Scanning electron microscope (SEM) image of FeCl3-intercalated CNTs assuming a bead-string structure with partially intercalated and swelled portions.

If chromatin is swelled suddenly in water and prepared for viewing in the electron microscope, the nucleosomes are evident as beads on a string, dsDNA being the string (Figure 12.28). The structure of the histone octamer core has been determined by X-ray crystallography without DNA by E. N. Moudrianakis s laboratory (Figure 12.29) and wrapped with DNA by T. J. 

Pfeffer in 1877 [523] subjected plant cell suspensions to different amounts of salt and observed the cells to shrink under hypertonic conditions and swell in hypotonic conditions. He concluded there was a semipermeable membrane separating the cell interior from the external solution, an invisible (under light microscope) plasma membrane. 

Light microscope (LM) studies showed that ECT caused distinct changes to the cellular structure of treated tumors. In the anodic area, the nuclei shrank and cytoplasmic structure disappeared.37 In the cathode area, the cells swelled and the interface among cells blurred. Repeatedly, one observes swelling in the cathode area (oedema) and dehydration around the anode — this key observation can only be explained in terms of electroosmotically driven water from anode to cathode, to be discussed in details in the Section on Mechanistic Studies. 

On development, the grains of the L4 emulsion swell to about 0.25 /un. However, the granularity observed on the topograph when viewed under the microscope is not a result of the grain of the film but is statistical shot noise , arising from the statistical variation in the number of developed grains per unit area. This... 

The majority of the inputs to the granule cells are excitatory, each of which provides a small depolarizing current to the membrane of the cell body. The point of contact between the axonal projection from the neuron and an adjacent cell is termed the s)mapse which under the electron microscope appears as a swelling at the end of the axon. Most synapses are excitatory and are usually located along the dendritic branches of the neuron. The contributions of the individual excitatory s)mapses are additive and, as a result, when an excitatory stimulus occurs a wave of depolarizing current travels down the axon to stimulate the adjacent cell body. However, some synapses are inhibitory, usually fewer in number and strategically located near the cell body. These synapses, when activated, inhibit the effects of any excitatory currents which may travel down the dendritic processes and thereby block their actions on the neuron (Figure 2.1). 

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