( ( of ( a ( breeding male ) ) ) ( , ( ovulation ( ( was ( observed ( in ( six ( of ( seven ( estrous cycles ) ) ) ) ) ) ) . ) ) ) )
(ROOT (S (PP (IN of) (NP (DT a) (VBG breeding) (NN male))) (, ,) (NP (NN ovulation)) (VP (VBD was) (VP (VBN observed) (PP (IN in) (NP (NP (CD six)) (PP (IN of) (NP (CD seven) (JJ estrous) (NNS cycles))))))) (. .)))
of a breeding male, ovulation was observed in six of seven estrous cycles.
(ROOT (S (NP (NNP Ovulation)) (VP (VBZ occurs) (SBAR (IN before) (S (NP (DT the) (NN endometrium)) (VP (VBZ thickens) (PP (IN in) (NP (JJ estrous) (NNS cycles))))))) (. .)))