( ( ( Two kinds ) ( of ( photoreceptor cells ) ) ) ( ( called ( ( ( rods and ) cones ) ( are ( in ( the retina ) ) ) ) ) . ) )
(ROOT (S (NP (NP (CD Two) (NNS kinds)) (PP (IN of) (NP (NN photoreceptor) (NNS cells)))) (VP (VBD called) (SBAR (S (NP (NNS rods) (CC and) (NNS cones)) (VP (VBP are) (PP (IN in) (NP (DT the) (NN retina))))))) (. .)))
Two kinds of photoreceptor cells called rods and cones are in the 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)))) (. .)))