In this picture, you can see the rat's nictitating membrane, which is a transparent, third eyelid.
If you take a close look at this picture you will be able to see the philtrum, which is located just underneath the nose but above the mouth. In this picture, you can also see its vibrissae, also called its whiskers. These whiskers contain blood filled sinus tissue.
Here, you can see the rat's pinna, also known as its ears. These are used to detect sound and can turn n the direction of sound.
Pregnant female rats develop teats(nipples) on there stomach as way to nourish there young when first born. they are made up of alveoli, or hollow cavities that produce milk.