Complex sentence: Antrochaonal polyps arise from the maxillary sinuses and the ethmoidal polyps arise from the ethmoidal sinuses, antrochoanal polyps are usually single and unilateral wereas ethmoidal polyps are muliple and bilateral.
Split into simpler sentences: Antrochaonal polyps arise from the maxillary sinuses and the ethmoidal polyps arise from the ethmoidal sinuses. Antrochoanal polyps are usually single and unilateral whereas ethmoidal polyps are multiple and bilateral.