( ( Lymphocytes ( and ( plasma cells ) ) ) ( ( form ( an ( outer layer ) ) ) . ) )
(ROOT (S (NP (NNS Lymphocytes) (CC and) (NN plasma) (NNS cells)) (VP (VBP form) (NP (DT an) (JJ outer) (NN layer))) (. .)))
Lymphocytes and plasma cells form an outer layer.
(ROOT (S (NP (NP (DT The) (JJ outer) (NN layer)) (PP (IN of) (NP (DT the) (NN sun)))) (VP (VBZ is) (VP (VBN made) (PRT (RP up)) (PP (IN of) (NP (NN plasma))))) (. .)))