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.
Paper is made from a variety of plant sources. Whether the fibers come from cotton or other plants such as linen, flax, jute, hemp, bamboo, rice straw or rattan, they all provide cellulose fibers or plant cells of varying dimensions. A sheet of paper is basically a thin layer of mingled cellulose fibers.