Which of the neuroglial cell types form myelin sheaths within the cns?

Everything in the universe originated from a single point. how was it possible for everything in the universe to have occupied a single point in space?

What is the name of the idea that energy cannot be created nor destroyed

Paleontologists have found plant fossils deep within the layers of the north polar region. these leaf fossils have been labeled as to the rock layers they were found in, with the lower numbers being layers close to the earth's surface and higher numbers representing deeper layers. according to the numbers of these four leaf fossils, what might you infer?