A researcher who is looking at part of a muscle under a microscope sees a plasma membrane and a layer of polysaccharide material that has a lot of thin collagen fibrils. What is the researcher most likely looking at?
O Sarcolemma
O Sarcoplasmic reticulum
O Myofibrils
Fascicle fibers

When studying under miscroscope part of the muscle, what the researcher is most likely looking at is sarcolemma.

Explanation:

The sarcolemma corresponds to the name of the specialized cell membrane of the muscle fiber, forming an assembly between the plasma membrane and the reticular and external laminae.  In its composition, besides the lipids, there are polysaccharides and collagen fibrils.

This myocyte cell membrane not only forms the external cover of the muscle cell, but is also capable of penetrating the sarcoplasm (cytoplasm) and constituting a trabecular formation, called T-tubules, with participation in the process of fiber contraction.

Regarding other options:

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