( ( ( Breast changes ) ( during ( ( physiological ( hormonal fluctuations ) ) ( ( influencing ( ( the actions ) ( of ( ( prolactin Puberty ) ( ( The ( major influence ) ) ( on ( breast growth ) ) ) ) ) ) ) ( during puberty ) ) ) ) ) ( ( is ( ( estrogen , ) ( which ( acts ( by ( ( the development ) ( of ( prolactin-dependent ( estrogen receptors ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NP (JJ Breast) (NNS changes)) (PP (IN during) (NP (NP (JJ physiological) (JJ hormonal) (NNS fluctuations)) (VP (VBG influencing) (NP (NP (DT the) (NNS actions)) (PP (IN of) (NP (NP (NNP prolactin) (NNP Puberty)) (NP (NP (DT The) (JJ major) (NN influence)) (PP (IN on) (NP (NN breast) (NN growth))))))) (PP (IN during) (NP (NN puberty))))))) (VP (VBZ is) (NP (NP (NN estrogen)) (, ,) (SBAR (WHNP (WDT which)) (S (VP (VBZ acts) (PP (IN by) (NP (NP (DT the) (NN development)) (PP (IN of) (NP (JJ prolactin-dependent) (NN estrogen) (NNS receptors)))))))))) (. .)))
Breast changes during physiological hormonal fluctuations influencing the actions of prolactin Puberty The major influence on breast growth during puberty is estrogen, which acts by the development of prolactin-dependent estrogen receptors.
(ROOT (S (NP (NNP Estrogen)) (VP (VBZ causes) (NP (NP (DT the) (NNS changes)) (PP (IN of) (NP (NN puberty))))) (. .)))