passages.id: split_4_validation_1490_passage
passages.type: progene_text
passages.text: The objective of this study was to investigate the levels of expression of steroid biosynthetic enzymes and steroidogenic acute regulatory protein ( StAR ) at different stages of ovarian follicular development in zebrafish ( Danio rerio ) , and to investigate the sites within the steroid biosynthetic pathway that may be regulated by gonadotropins .