Complex sentence: After addition of APS and TEMED to the stacking gel solution, it is poured onto the solid separation gel and and a suitable sample comb ist inserted between the glass plates without creating bubbles.
Split into simpler sentences: After addition of APS and TEMED to the stacking gel solution, it is poured on top of the solid separation gel. Afterwards, a suitable sample comb ist inserted between the glass plates without creating bubbles.