Before the bulbs on your scalp wither away and are no longer able to produce hair, they replace the thick dark terminal hair that you are used to seeing with skinny, hardly noticeable vellus hair. If you look carefully in a magnifying mirror, you will most likely see some vellus hair emerging from what looks like empty follicles. This is especially true in Male Pattern Baldness, where hair bulbs cycle down - producing terminal hairs when the bulbs are large and powerful, then replacing these normal scalp hairs with vellus hair as the bulb decreases in size over a period of years. In most people, thinning hair lasts for many years before hair bulbs begin to atrophy and are no longer able to manufacture hair at all. Vitamins aren't the only factor in hair growth.
Follicles have two kinds of protein molecules on their cell membranes.
One group of proteins receives testosterone, while the other group repels it. In this way the follicle can balance the amount of hair growth direction that it receives from the body. How many of each type of protein receptors a person has seems to be genetically predetermined. Hence, Male Pattern Baldness is a trait passed from generation to generation. In men, these receptor cells seem to be located in certain areas of the scalp, yet are not found in others.