Estrogen does not play a major role in

Oxytocin plays an important in milk ejection. 

Estrogens produce wide ranging actions such as stimulation of growth and activities of female secondary sex organs, development of growing ovarian follicles, appearance of female secondary sex characters (e.g., high pitch of voice, etc.), mammary gland development.High concentration of LH as well as estrogen, causes the release of an ovum (the process is ovulation) from the graffian follicle.