Oestrogen is produced by enzyme modification(in the stroma) of testosterone produced by the thecae of the developing follicle. Oestrogen has several effects: 1. It stimulates further growth of the follicle. 2. It promotes repair of the endometrium 3. It acts as a feedback inhibitor of the secretion of FSH from the anterior pituitary gland. 4. From about day 11 it has a positive feedback action on the secretion of both LH and FSH.