The glial cells outnumber theneurones and the two cell types occupy a comparable amount of space in nervous tissue. The main glial cell types are, inthe central nervous system, astrocytes and oligodendrocytes and, in the peripheral nervous system, Schwann cells, entericglial cells and satellite cells.he glial cells outnumber theneurones and the two cell types occupy a comparable amount of space in nervous tissue. The main glial cell types are, inthe central nervous system, astrocytes and oligodendrocytes and, in the peripheral nervous system, Schwann cells, entericglial cells and satellite cells.
1 Cytosine is found in both DNA and RNA, but thymine is only found in DNA and uracil is only found in RNA.  A nucleotide is formed when a phosphate attahes to the 5' carbon of the sugar and one of the nitrogenous baseses attaches to the 1' carbon of the sugar.
RNA nucleotides contain ribose while DNA contains deoxyribose (a type of ribose that lacks one oxygen atom), and in RNA the nucleotide uracil substitutes for thymine, which is present in DNA. Ribonucleic acid.