At the midpoint of the menstrual cycle, the tertiary follicle (also called the graafian follicle) containing the secondary oocyte moves towards the surface of the ovary. Because of fsh and lh, the follicle expands and completes meiosis i. It then stops at metaphase of meiosis ii. After meiosis i, the first polar body is expelled. Stigma: apex of the protrusion of the tertiary follicle from the ovary. Lh increase causes the secondary oocyte to be released. Within hours of exposure to high amounts of lh, the follicle reorganizes its program of gene expression. A while after the lh peak, local blood flow increases in the outer layer of the follicular wall, and plasma proteins leak into the tissues resulting in edema. Edema and release of active compounds (like prostaglandins, histamine, vasopressin, and plasminogen activator) start the reactions that result in the production of matric metalloproteinases. Matric metalloproteinases: lytic enzymes that degrade components of the extracellular matrix.