( ( ( ( ( ( Two types ) ( of ( photoreceptor cells ) ) ) , ) ( ( rods and ) cones ) ) , ) ( ( mediate ( the ( response ( to ( light ( in ( the ( mammalian retina ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NP (NP (CD Two) (NNS types)) (PP (IN of) (NP (NN photoreceptor) (NNS cells)))) (, ,) (NP (NNS rods) (CC and) (NNS cones)) (, ,)) (VP (VB mediate) (NP (DT the) (NN response) (S (VP (TO to) (VP (VB light) (PP (IN in) (NP (DT the) (JJ mammalian) (NN retina)))))))) (. .)))
Two types of photoreceptor cells, rods and cones, mediate the response to light in the mammalian retina.
(ROOT (S (NP (NP (DT The) (JJ light-sensing) (NNS cells)) (PP (IN in) (NP (DT the) (NN retina)))) (VP (VBP are) (VP (VBN called) (NP (NNS rods) (CC and) (NNS cones)))) (. .)))