Top-down  an apex of professors and doctors buttressed by the holders of college degrees (many of them lower-level administrators, teachers, and researchers within the system).
( ( ( Top-down ( an apex ) ) ( of ( ( professors and ) doctors ) ) ) ( ( ( buttressed ( by ( ( the holders ) ( of ( college degrees ) ) ) ) ) ( -LRB- ( ( ( ( many ( of ( ( ( ( ( them lower-level ) administrators ) , ) teachers ) , ) ) ) and ) ( researchers ( within ( the system ) ) ) ) -RRB- ) ) ) . ) )
(ROOT (S (NP (NP (JJ Top-down) (DT an) (NN apex)) (PP (IN of) (NP (NNS professors) (CC and) (NNS doctors)))) (VP (VBN buttressed) (PP (IN by) (NP (NP (DT the) (NNS holders)) (PP (IN of) (NP (NN college) (NNS degrees))))) (PRN (-LRB- -LRB-) (NP (NP (NP (JJ many)) (PP (IN of) (NP (NP (ADJP (NP (PRP them)) (JJ lower-level)) (NNS administrators)) (, ,) (NP (NNS teachers)) (, ,)))) (CC and) (NP (NP (NNS researchers)) (PP (IN within) (NP (DT the) (NN system))))) (-RRB- -RRB-))) (. .)))
Every professor and doctor has a college degree. 
( ( Every ( ( professor and ) doctor ) ) ( ( has ( a ( college degree ) ) ) . ) )
(ROOT (S (NP (DT Every) (NN professor) (CC and) (NN doctor)) (VP (VBZ has) (NP (DT a) (NN college) (NN degree))) (. .)))