human_reference_atlas Homo sapiens secondary ovarian follicle pre-antral follicle preantral follicle ovary secondary follicle pre-ovulatory follicle folliculus ovaricus secondarius FMA:18637 AS MA:0002908 secondary egg follicle secondary ovarian follicle UBERON:0000036 uberon secondary follicle of ovary antral follicle of ovary consider adopting distinction in MA EMAPA:35632 A maturing ovarian follicle that has two more more layers of granulosa cells, up to the onset of antrum formation. secondary follicle secondary ovarian follicle ovarian follicle preantral follicle