These genetic variants are believed to cause changes in the way the bodyâs T cells behave. T cells are immune system cells that normally fight off harmful invaders, such as viruses and bacteria. In people with psoriasis, however, T cells also attack healthy skin cells by mistake. This immune system response results in a range of reactions, including: 1  enlargement of blood vessels in the skin.  increase in white blood cells that stimulate the skin to produce new cells more quickly than usual.
Teeth. Zebra have several types of teeth that help them survive in their habitats. In the front of their mouths, zebra use their strong incisors for biting off grass and other vegetation. In the rear of their mouths, zebra have molars and premolars to grind down their food.
The mountain zebra has two subspecies: Hartmann's and the Cape mountain zebra. These species mostly live in southern Africa, particularly Namibia and western South Africa. Compared to Burchell's and Grevy's zebra, this species prefers mountainous areas.urchell's Zebra. As is typical in the sciences, two species of zebra are named after the scientists who discovered and identified them. Burchell's zebra, which also is referred to as the plains zebra, is the most numerous of the three species.