biostudies-literatureCarver JJNIH Intramural Research Program National Institute of Environmental Health SciencesNICHD NIH HHSNIDDK NIH HHSNational Institute of Diabetes and Digestive and Kidney DiseasesNIGMS NIH HHSNational Institute of Child Health and Human Development1107-1128https://www.ebi.ac.uk/biostudies/studies/S-EPMC11565245biostudies-literatureUnknown111(5)Previous studies have suggested that adamts9 (a disintegrin and metalloprotease with thrombospondin type-1 motifs, member 9), an extracellular matrix (ECM) metalloprotease, participates in primordial germ cell (PGC) migration and is necessary for female fertility. In this study, we found that adamts9 knockout (KO) led to reduced body size, and female-to-male sex conversion in late juvenile or adult zebrafish; however, primary sex determination was not affected in early juveniles of adamts9 KO. Overfeeding and lowering the rearing density rescued growth defects in female adamts9 KO fish but did not rescue defects in ovarian development in adamts9 KO. Delayed PGC proliferation, significantly reduced number and size of Stage IB follicles (equivalent to primary follicles) in early juveniles ofBiology of reproductionAdamts9 is required for the development of primary ovarian follicles and maintenance of female sex in zebrafish†.PMC11565245R00 DK132460DK132460-01R15 GM100461R15 HD109785K99 DK132460ES102965HD109785Hung-Chang Yao HCarver JJAmato CMZhu YfalseAdamts9 is required for the development of primary ovarian follicles and maintenance of female sex in zebrafish†.Previous studies have suggested that adamts9 (a disintegrin and metalloprotease with thrombospondin type-1 motifs, member 9), an extracellular matrix (ECM) metalloprotease, participates in primordial germ cell (PGC) migration and is necessary for female fertility. In this study, we found that adamts9 knockout (KO) led to reduced body size, and female-to-male sex conversion in late juvenile or adult zebrafish; however, primary sex determination was not affected in early juveniles of adamts9 KO. Overfeeding and lowering the rearing density rescued growth defects in female adamts9 KO fish but did not rescue defects in ovarian development in adamts9 KO. Delayed PGC proliferation, significantly reduced number and size of Stage IB follicles (equivalent to primary follicles) in early juveniles of2024-01-01T00:00:00Z2024 Nov2026-04-08T09:58:21.157Z2026-04-08T01:10:42.894ZS-EPMC115652453918072210.1093/biolre/ioae127