AMH, or anti-mullerian hormone, is a substance produced by granulosa cells in ovarian follicles. It is first made in primary follicles that advance from the primordial follicle stage. At these stages follicles are microscopic and can not be seen by ultrasound. AMH production is highest in pre-antral and small antral stages (less than 4mm diameter) of development. Production decreases ... https://www.durgasfertility.com/patient-education/infertility-testing/amh-testing