After extracting total RNA , I ran an agarose gel with TAE buffer, observing two bands representing the 18S and 28S(see attached 1).

The same RNA was then seprated using a denaturing agarose gel, and extra bands betwwen 18S and 18S were obtained (see attached 2).

What are these extra bands? degradation product or other type of RNA(eg tRNA,snRNA), or is there any explaination?

Thanks a lot