Amnion & Chorion Tissue
Also known as the amniotic sac, the amnion tissue is composed of a single layer of epithelium cells, thin reticular fibers (basement membrane), a thick compact layer, and a fibroblast layer. The tissue itself contains collagen types III, IV, and V1. Amniotic tissue is derived from trophoblasts. These cells cover the developing embryo and primarily exhibit major histocompatibility complex (MHC) Class II antigens, not MHC Class I, which are present in all cadaveric tissue and are responsible for rapid rejection of the allograft.
Chorion tissue consists of a reticular layer, a basement membrane containing a layer of dense connective tissue and a trophoblast layer. In addition, the reticular and basement membrane layers contain collagen types I, III, IV, V, and VI2.