The replacement of a diseased organ by a transplant (healthy tissue
or organ) is called transplantation. In the early 1940 Medawar explained
the nature of graft (transplant) rejection while working with the burn patients
of World War II. In his observations the following features were made clear.
1. graft of skin from one region of the body to another in the same patient
was easily accepted, 2. grafts obtained from close relatives like brother or
sister, were rejected 3. when a second graft was performed, by obtaining the
tissue from the same donor, the rejection reaction occurred with greater
intensity and speed. The graft or transplant leads to various complications in
the host body. (Transplantation immunology)
They are mediated by the host’s immune response. Very often the transplant gets rejected or may lead to graft verses host reaction or disease. Before discussing the nature and implications of this rejection phenomenon let us look into the terms involved in various types of grafts.
Classification of grafts : (Transplantation immunology)
The graft can be classified into four major types.
1. Autograft : The tissue of the original donor is grafted back into the same
donor. For example, skin graft from thigh to face in severely deformed case
of burnt individuals (plastic surgery).
2. Isograft : Graft between syngeneic individuals (ie., identical genetic
constitutuion). For example, clones or identical twins.
3. Allograft : (Homograft). Graft between allogenic individuals (ie.,
members of the same species but of different genetic constitution. For
example, kidney transplanted from one human to another.
4. Xenograft : (Heterograft). Graft between xenogenic individuals (ie.,
different genetic lineage). For example organ transplanted from pig to
human, baboon to human.
Related Topics in Zoology:
- Microbiology Introduction and History of Medical Microbiology
- Pasteur, Koch, Lister
- Structure of Viruses
- Viral genetics
- Virus Culture
- Viral Diseases
- Bacteria Structure Culture
- Bacterial Genetics
- Bacterial Diseases
- Protozoan microbiology
- Pathogenecity of Microorganisms
- Antimicrobial Resistance
- Antibiotics and Chemotherapy
- AIDS – HIV