hair growth cycle
We’ve all watched television programs like “CSI: Crime Scene Investigation” and “Law and Order.” Shows like these simplify the investigative process that investigators conduct in trying to solve the mysteries behind crimes. If you’ve paid close attention, you may have noticed investigators collecting and examining hair as evidence in crime cases. How is the hair used to solve the crime? The study of the hair follicles found at the scene goes beyond the hair color.
Three layers of the hair shaft are used in determining how a crime was committed and who the criminal may be. The medulla, the innermost core of the hair, can be used to determine the race or ethnicity of the potential perpetrator.
The cortex is the layer over the medulla and is used to compare one hair to another. Microscopic air bubbles and pigment granules help scientists distinguish between the hair types. The outermost layer, the cuticle, can be used to determine the species (if the hair belongs to an animal) through analysis of the patterns of scales that cover the cortex.
In terms of investigation, the root of the hair can be one of the most useful pieces of evidence. By the root (or lack thereof), scientists can tell if the hair was shed naturally, pulled out, or cut off. The root is where investigators can find DNA to help precipitate their analysis. If a hair is pulled out during the anagen phase of the hair growth cycle a root bulb will appear with follicular tissue. This tissue has nuclear DNA which helps create a DNA profile unique to the hair’s owner.
During the catagen stage, the root of the hair pulls away from the shaft, and the hair is easily pulled from the head. The root bulb is less round and more elongated in this phase. In the final stage, the telogen phase, the hair sheds naturally and has a club-shaped root bulb. These two phases do not produce a follicular tag, which means nuclear DNA cannot be harvested from hairs in the catagen and telogen phases. However, mitochondrial DNA may be found in just the hair and can help to narrow down subjects, though it cannot distinguish between siblings.
Hair is also useful in chemical tests since it is often the only evidence still remaining after other bodily evidence has disappeared. Scientists can determine the presence of chemicals, poisons, heat treatments, and more. The important thing to note about the use of hair in investigations is that it is only one piece of an investigative puzzle. Hair cannot be used as evidence on its own. However, it can be very useful along with other pieces of evidence. Who knew your hair held so much information?
Bertino, Anthony J., and Patricia Nolan. Bertino. Forensic Science: Fundamentals & Investigations. Mason, OH: South-Western Cengage Learning, 2009.
A study published in the journal Dermatology shows that women lose more hair during autumn than they do in other seasons. Swedish researchers gathered a sample of 823 women and tracked their hair growth and shedding cycles.
Each person goes through the hair growth and shedding cycle. In the anagen phase also known as the growth phase of the hair follicle, new hair cells are produced. The catagen phase is where the hair is no longer growing but the follicle is shrinking. The final stage, the telogen phase, occurs when the hair is in a resting state, no longer growing, but on the verge of shedding. The hair stays in this resting state for about three months when it begins to shed, and the anagen phase begins gradually. Therefore, the average patient loses about 100 hairs per day. At the end of the telogen phase, the hair cycle of growth begins again, and if you could watch the follicular opening you would see a new hair emerge in a couple of weeks.
Though each individual’s hair growth and shedding cycle schedules will vary slightly, the researchers found that the women studied had the highest percentage of hair in the telogen stage at the end of summer. This means that after a period of time, these women will have some hair loss since the resting phase is always followed by a shedding. During this time, the patient may feel that his or her hair is thinning with the natural loss of hair that is occurring. The same sort of hair-loss phasing happens, though with a lower percentage of hair, in the spring as well. Researchers speculate that this extra amount of lost hair may be brought about by evolution, since the body seems to hold on to hair during the warmer months to protect the scalp from the summer sun.
For those people who experience hair loss with no growth to follow it, The Griffin Center of Hair Restoration and Research offers both non-surgical and surgical treatment and prevention options for women’s hair loss. Most commonly this hair loss is the result of female patterned hair loss, and the minuturization of hairs which eventually do not return. This process can be slowed and even in some cases reversed with treatment.
Contact us for more information on hair loss or to schedule an appointment with Dr. Edmond Griffin, hair restoration specialist. You can also connect with us on Twitter and Facebook for daily news and updates.