So estrogen is a steroid hormone that means it's lipid soluble. So that means it can easily travel across a cell membrane and it basically binds to the protein receptor inside that cell and eventually it enters, estrogen enters our nucleus of the cell and it acts on the cell on a transcriptional level, it influences the transcription of our cell. Now, estrogen itself is stimulated by our luteinizing hormone as well as the follicle stimulating hormone that are released by the interior pituitary gland. And FSH as well as LH are both stimulated by the gonadotropin releasing hormone released by the hypothalamus. So estrogen is basically released by two structures. So estrogen is initially released by our ovarian follicle, this structure here.