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.
For example, whether you are buying individual conductors or sheathed cable, the wire gauge labeling will help you buy wires that are sized correctly for the electrical load they will carry. The labeling on the wire also tells what the wire is made of--either aluminum or copper. But wires also carry another form of labeling that serves to identify the nature of the plastic or vinyl insulating sheath that covers the individual conductors.