**2. Types of grafts**

Grafts of different species can cause different degrees of immune response to recipients. Generally, the greater the difference between the species, the more likely that it is that there will be a stronger immunological rejection. Accordingly, this section will discuss the types of graft. Liver grafts often mainly consist of four types: autograft, isograft, allograft and xenograft (Figure 1). The definitions and features of all grafts will be now be described in detail and the effects of different grafts on the body's immune system also will be introduced.

Fig. 1. Types of grafts
