( ( In mammals ) ( , ( ( olfactory receptors ) ( ( are ( expressed ( on ( ( the surface ) ( of ( ( the ( olfactory epithelium ) ) ( in ( the ( nasal cavity ) ) ) ) ) ) ) ) ) . ) ) ) )
(ROOT (S (PP (IN In) (NP (NNS mammals))) (, ,) (NP (JJ olfactory) (NNS receptors)) (VP (VBP are) (VP (VBN expressed) (PP (IN on) (NP (NP (DT the) (NN surface)) (PP (IN of) (NP (NP (DT the) (JJ olfactory) (NN epithelium)) (PP (IN in) (NP (DT the) (JJ nasal) (NN cavity))))))))) (. .)))
In mammals, olfactory receptors are expressed on the surface of the olfactory epithelium in the nasal cavity.
(ROOT (S (PP (IN In) (NP (NNS mammals))) (, ,) (NP (NN air)) (VP (VBZ is) (VP (VBN warmed) (CC and) (VBN humidified) (PP (IN in) (NP (DT the) (JJ nasal) (NN cavity))))) (. .)))