Final answer:
A skin graft from a foreign donor like a pig is referred to as a xenograft. These grafts have a high risk of immune rejection, which is why immunosuppressive drugs are often needed post-transplant.
Step-by-step explanation:
The term used for a skin graft that comes from a foreign donor, such as a pig, is a xenograft. This type of tissue transplantation involves transferring tissues from one species, like a pig, to a different species, such as a human. The risk of rejection is high in xenografts because the recipient's immune system can recognize the donated tissue as foreign.
Rejection happens when the immune system identifies the transplant as non-self due to different major histocompatibility complex markers. This can activate the immune response, where cytotoxic T cells can destroy the grafted cells. To reduce this risk, immunosuppressive drugs may be used post-transplantation.