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 and insulators-Conductors are materials that allow electricity to flow easily. 2  Most types of metal are good conductors, which is why we use metal for electrical wire. 3  Copper is a good conductor and isn't too expensive, so it's used a lot for the wiring in homes today. Copper is a good conductor and isn't too expensive, so it's used a lot for the wiring in homes today. 2  Insulators are the opposite of conductors. 3  An insulator is a material that doesn't carry electricity. 4  Insulators are important because they can protect us from electricity.