( ( The ( ( top and ) bottom ) ) ( ( are ( defined ( by ( ( cellular layers ) ( called ( ( upper and ) ( lower epidermis ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (DT The) (NN top) (CC and) (NN bottom)) (VP (VBP are) (VP (VBN defined) (PP (IN by) (NP (NP (JJ cellular) (NNS layers)) (VP (VBN called) (NP (NP (JJ upper)) (CC and) (NP (JJR lower) (NNS epidermis)))))))) (. .)))
The top and bottom are defined by cellular layers called upper and lower epidermis.
(ROOT (S (NP (NNS Melanocytes)) (VP (VBP are) (VP (VBN located) (PP (IN in) (NP (NP (DT the) (JJ bottom) (NN layer)) (PP (IN of) (NP (DT the) (NNS epidermis))))))) (. .)))