So, from forever ago, I'm going to work on some of those 'ideas' in my head and start clearing out some of the paper clutter I have at home with all my little notes. This is as good of a place as any to put those thoughts, right? This time, it is from looking through papers on hair and coat types in rats. So, I'll start compiling some of the information I've gathered here until I get into researching it deeper. So, a mini article to keep me on track...

The part and type of hair that I'm interested in is the part on the body that contains pigment. The middle layer of a hair is called the cortex, and this is where the pgiment is contained within keratinized cells (cells that are thickened with the protein, keratin). There are two types of hair on the body. The guard hairs are longer and are used for waterproofing and protection. The undercoat hairs and shorter and more dense and help insulate the body. But, before we get much further, it is important to note how the hair is produced within the follicles. Follicles are complete with blood, nerves, tiny muscles (responsible for piloerection), and matrix cells, which are the cells that keratinize and push upward to form hairs. The follicle goes through a specific gene-regulated growth cycle that is important as well. There are three phases: anagen, catagen, and telogen. The anagen phase is the active phase of hair growth. The catagen phase is when the growth is shutting down. And, the telogen phases is the rest phase, and it is during this time that hair can also fall out. Since genes and hormones play a big role in these growth stages, it is easy to imagine the mutations and changes that can affect the hair growth patterns. For instance, the anagen phase is sensitive to thyroid hormones, and if too low, the follicle will enter the catagen phase prematurely, leading to hair loss. This is just one of many examples though. Hair growth patterns are also very interesting. Not all follicles go through the same phase at the same time. The phases follow in a wave like pattern from the front end of the body to the back, and from the belly to the back. That is why you can see the molting pattern on a growing rat. It is the mid point between the phases of growth in the follicles, and it can produce some interesting results!

So, now the fun part...mutations!!

That will be the next installment!

Reference:
http://www.spflrc.org/user/rats/CoatTypes.htm