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Cornea transplant in humans is almost never rejected. This is because:
A
It is composed of enucleated cells
B
It is a non-living layer
C
Its cells are least penetrable by bacteria
D
It has no blood supply
Detailed Solution
Rejection of a transplanted organ is brought about by the immune system of the recipient: lymphocytes (cell-mediated immunity) and antibodies recognise the graft as foreign and attack it.
These immune cells and antibodies reach a graft through the blood vessels and lymphatics.
The cornea is avascular: it has no blood supply (and no lymphatic vessels). It gets its oxygen directly from the air and its nutrients from the aqueous humour and tears.
Because there is no blood supply, the immune cells of the recipient do not come in contact with the transplanted cornea, so it is not recognised as foreign and is almost never rejected.
The cornea is made of living, nucleated cells, so it is neither a non-living layer nor composed of enucleated cells.
So a cornea transplant is almost never rejected because it has no blood supply.
These immune cells and antibodies reach a graft through the blood vessels and lymphatics.
The cornea is avascular: it has no blood supply (and no lymphatic vessels). It gets its oxygen directly from the air and its nutrients from the aqueous humour and tears.
Because there is no blood supply, the immune cells of the recipient do not come in contact with the transplanted cornea, so it is not recognised as foreign and is almost never rejected.
The cornea is made of living, nucleated cells, so it is neither a non-living layer nor composed of enucleated cells.
So a cornea transplant is almost never rejected because it has no blood supply.