Why are the interactions of hormones and tissues considered to be feedback mechanisms

In women's menstrual lining, the tissues will keep on activating hormones until the right thickness of the lining of the menstrual is achieved, which would fall on the positive feedback. Then, when the estrogen hormones are being passed on the blood, it travels to the pituitary gland to tell the follicle stimulating hormone to stop producing.

Aplant cell has vacuoles and a cell wall