The follicular phase begins with an increase in follicle-stimulation hormone (FSH), which causes increases in luteinizing hormone (LH) and gonadotropin-releasing hormone (GnRH). Concurrent increases in estrogen levels cause increases in progesterone, stimulating proliferation of the endometrium.
Examples of insulators include plastics, Styrofoam, paper, rubber, glass and dry air. The division of materials into the categories of conductors and insulators is a somewhat artificial division. It is more appropriate to think of materials as being placed somewhere along a continuum.
1 Conductors conduct electrical current very easily because of their free electrons. 2  Insulators oppose electrical current and make poor conductors. 3  Some common conductors are copper, aluminum, gold, and silver. 4  Some common insulators are glass, air, plastic, rubber, and wood.