Estrogen (estradiol and androgen), progesterone, gonadotropin (GnRH), follicle stimulating hormone (FSH) and lutenizing hormone (LH) are the five hormones needed for the process.
The hormone which is produced in the hypothalamus is the GnRH and this is the hormone which regulates the estrogen. I believe this would be the first one produced by the pituitary, because FSH and LH come AFTER the production of GNRH. Hope this helps!
The hypothalamus is a neuro-endocrine system, active in numerous processes. First, it conducts many slow actions, such as growth, by checking the pituitary gland, the main center of production of hormones.
The hypothalamus is the source of our emotions and basic needs of hunger, thirst and sex.
Very important is the fact that, by a pulsating secretion, controls the pituitary activity and thereby, the ovarian cycle, cycle whose peak is ovulation. A normal menstrual cycle would be impossible without some signs of ovarian steroid hormones, and without the involvement of brain centers.
The ovaries also influences, through a negative feedback mechanism, pulsed secretion of the hypothalamus and pituitary. This translates into the fact that hormones secreted by the hypothalamus and "processed" by the pituitary, come through blood to the ovaries, and they secrete estrogen and progesterone which are returning again to the brain.This, according to the needs of the body, limits or extends beyond the production of hormones.
Your body produces two prominent hormones: estrogen and progesterone. Both hormones are manufactured in your ovaries and play important roles in a your reproductive system. Estrogen is the hormone responsible for the healthy development of your female sexual characteristics such as your breasts, vagina, your menstrual cycle, body shape, and hair growth under the arms and around the pubic region. Progesterone, on the other hand is the other hormone that regulates your menstruation. These two hormones, along with testosterone and DHEA work together to provide great health for you. Along with the unisex follicle stimulating hormone (FSH) and luteinizing hormone (LH), all of these hormones play specific functions in a your reproductive system.